Endogenous proteins that inhibit or inactivate COMPLEMENT C3B. They include COMPLEMENT FACTOR H and COMPLEMENT FACTOR I (C3b/C4b inactivator). They cleave or promote the cleavage of C3b into inactive fragments, and thus are important in the down-regulation of COMPLEMENT ACTIVATION and its cytolytic sequence.
A glycoprotein that is central in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C3 can be cleaved into COMPLEMENT C3A and COMPLEMENT C3B, spontaneously at low level or by C3 CONVERTASE at high level. The smaller fragment C3a is an ANAPHYLATOXIN and mediator of local inflammatory process. The larger fragment C3b binds with C3 convertase to form C5 convertase.
A glycoprotein that is important in the activation of CLASSICAL COMPLEMENT PATHWAY. C4 is cleaved by the activated COMPLEMENT C1S into COMPLEMENT C4A and COMPLEMENT C4B.
Serum proteins that negatively regulate the cascade process of COMPLEMENT ACTIVATION. Uncontrolled complement activation and resulting cell lysis is potentially dangerous for the host. The complement system is tightly regulated by inactivators that accelerate the decay of intermediates and certain cell surface receptors.
Serum proteins that inhibit, antagonize, or inactivate COMPLEMENT C1 or its subunits.
A 53-kDa protein that is a positive regulator of the alternate pathway of complement activation (COMPLEMENT ACTIVATION PATHWAY, ALTERNATIVE). It stabilizes the ALTERNATIVE PATHWAY C3 CONVERTASE (C3bBb) and protects it from rapid inactivation, thus facilitating the cascade of COMPLEMENT ACTIVATION and the formation of MEMBRANE ATTACK COMPLEX. Individuals with mutation in the PFC gene exhibit properdin deficiency and have a high susceptibility to infections.
The larger fragment generated from the cleavage of COMPLEMENT C3 by C3 CONVERTASE. It is a constituent of the ALTERNATIVE PATHWAY C3 CONVERTASE (C3bBb), and COMPLEMENT C5 CONVERTASES in both the classical (C4b2a3b) and the alternative (C3bBb3b) pathway. C3b participates in IMMUNE ADHERENCE REACTION and enhances PHAGOCYTOSIS. It can be inactivated (iC3b) or cleaved by various proteases to yield fragments such as COMPLEMENT C3C; COMPLEMENT C3D; C3e; C3f; and C3g.
Serum glycoproteins participating in the host defense mechanism of COMPLEMENT ACTIVATION that creates the COMPLEMENT MEMBRANE ATTACK COMPLEX. Included are glycoproteins in the various pathways of complement activation (CLASSICAL COMPLEMENT PATHWAY; ALTERNATIVE COMPLEMENT PATHWAY; and LECTIN COMPLEMENT PATHWAY).
The sequential activation of serum COMPLEMENT PROTEINS to create the COMPLEMENT MEMBRANE ATTACK COMPLEX. Factors initiating complement activation include ANTIGEN-ANTIBODY COMPLEXES, microbial ANTIGENS, or cell surface POLYSACCHARIDES.
The smaller fragment formed when complement C4 is cleaved by COMPLEMENT C1S. It is an anaphylatoxin that causes symptoms of immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE) but its activity is weaker than that of COMPLEMENT C3A or COMPLEMENT C5A.
A component of the CLASSICAL COMPLEMENT PATHWAY. C2 is cleaved by activated COMPLEMENT C1S into COMPLEMENT C2B and COMPLEMENT C2A. C2a, the COOH-terminal fragment containing a SERINE PROTEASE, combines with COMPLEMENT C4B to form C4b2a (CLASSICAL PATHWAY C3 CONVERTASE) and subsequent C4b2a3b (CLASSICAL PATHWAY C5 CONVERTASE).
Serine proteases that cleave COMPLEMENT C3 into COMPLEMENT C3A and COMPLEMENT C3B, or cleave COMPLEMENT C5 into COMPLEMENT C5A and COMPLEMENT C5B. These include the different forms of C3/C5 convertases in the classical and the alternative pathways of COMPLEMENT ACTIVATION. Both cleavages take place at the C-terminal of an ARGININE residue.
A glycine-rich, heat-labile serum glycoprotein that contains a component of the C3 CONVERTASE ALTERNATE PATHWAY (C3bBb). Bb, a serine protease, is generated when factor B is cleaved by COMPLEMENT FACTOR D into Ba and Bb.
The smaller fragment generated from the cleavage of complement C3 by C3 CONVERTASE. C3a, a 77-amino acid peptide, is a mediator of local inflammatory process. It induces smooth MUSCLE CONTRACTION, and HISTAMINE RELEASE from MAST CELLS and LEUKOCYTES. C3a is considered an anaphylatoxin along with COMPLEMENT C4A; COMPLEMENT C5A; and COMPLEMENT C5A, DES-ARGININE.
Complement activation initiated by the interaction of microbial ANTIGENS with COMPLEMENT C3B. When COMPLEMENT FACTOR B binds to the membrane-bound C3b, COMPLEMENT FACTOR D cleaves it to form alternative C3 CONVERTASE (C3BBB) which, stabilized by COMPLEMENT FACTOR P, is able to cleave multiple COMPLEMENT C3 to form alternative C5 CONVERTASE (C3BBB3B) leading to cleavage of COMPLEMENT C5 and the assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX.
A subcomponent of complement C1, composed of six copies of three polypeptide chains (A, B, and C), each encoded by a separate gene (C1QA; C1QB; C1QC). This complex is arranged in nine subunits (six disulfide-linked dimers of A and B, and three disulfide-linked homodimers of C). C1q has binding sites for antibodies (the heavy chain of IMMUNOGLOBULIN G or IMMUNOGLOBULIN M). The interaction of C1q and immunoglobulin activates the two proenzymes COMPLEMENT C1R and COMPLEMENT C1S, thus initiating the cascade of COMPLEMENT ACTIVATION via the CLASSICAL COMPLEMENT PATHWAY.
C5 plays a central role in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C5 is cleaved by C5 CONVERTASE into COMPLEMENT C5A and COMPLEMENT C5B. The smaller fragment C5a is an ANAPHYLATOXIN and mediator of inflammatory process. The major fragment C5b binds to the membrane initiating the spontaneous assembly of the late complement components, C5-C9, into the MEMBRANE ATTACK COMPLEX.
The minor fragment formed when C5 convertase cleaves C5 into C5a and COMPLEMENT C5B. C5a is a 74-amino-acid glycopeptide with a carboxy-terminal ARGININE that is crucial for its spasmogenic activity. Of all the complement-derived anaphylatoxins, C5a is the most potent in mediating immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE), smooth MUSCLE CONTRACTION; HISTAMINE RELEASE; and migration of LEUKOCYTES to site of INFLAMMATION.
The large fragment formed when COMPLEMENT C4 is cleaved by COMPLEMENT C1S. The membrane-bound C4b binds COMPLEMENT C2A, a SERINE PROTEASE, to form C4b2a (CLASSICAL PATHWAY C3 CONVERTASE) and subsequent C4b2a3b (CLASSICAL PATHWAY C5 CONVERTASE).
Enzymes that activate one or more COMPLEMENT PROTEINS in the complement system leading to the formation of the COMPLEMENT MEMBRANE ATTACK COMPLEX, an important response in host defense. They are enzymes in the various COMPLEMENT ACTIVATION pathways.
Serum proteins with an electrophoretic mobility that falls between ALPHA-GLOBULINS and GAMMA-GLOBULINS.
A 105-kDa serum glycoprotein with significant homology to the other late complement components, C7-C9. It is a polypeptide chain cross-linked by 32 disulfide bonds. C6 is the next complement component to bind to the membrane-bound COMPLEMENT C5B in the assembly of MEMBRANE ATTACK COMPLEX. It is encoded by gene C6.
A 206-amino-acid fragment in the alpha chain (672-1663) of C3b. It is generated when C3b is inactivated (iC3b) and its alpha chain is cleaved by COMPLEMENT FACTOR I into C3c (749-954), and C3dg (955-1303) in the presence COMPLEMENT FACTOR H.
A 302-amino-acid fragment in the alpha chain (672-1663) of C3b. It is generated when C3b is inactivated (iC3b) and its alpha chain is cleaved by COMPLEMENT FACTOR I into C3c, and C3dg (955-1303) in the presence COMPLEMENT FACTOR H. Serum proteases further degrade C3dg into C3d (1002-1303) and C3g (955-1001).
All blood proteins except albumin ( = SERUM ALBUMIN, which is not a globulin) and FIBRINOGEN (which is not in the serum). The serum globulins are subdivided into ALPHA-GLOBULINS; BETA-GLOBULINS; and GAMMA-GLOBULINS on the basis of their electrophoretic mobilities. (From Dorland, 28th ed)
A 63-kDa serum glycoprotein encoded by gene C9. Monomeric C9 (mC9) binds the C5b-8 complex to form C5b-9 which catalyzes the polymerization of C9 forming C5b-p9 (MEMBRANE ATTACK COMPLEX) and transmembrane channels leading to lysis of the target cell. Patients with C9 deficiency suffer from recurrent bacterial infections.
Molecules on the surface of some B-lymphocytes and macrophages, that recognize and combine with the C3b, C3d, C1q, and C4b components of complement.
The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.
A 77-kDa subcomponent of complement C1, encoded by gene C1S, is a SERINE PROTEASE existing as a proenzyme (homodimer) in the intact complement C1 complex. Upon the binding of COMPLEMENT C1Q to antibodies, the activated COMPLEMENT C1R cleaves C1s into two chains, A (heavy) and B (light, the serine protease), linked by disulfide bonds yielding the active C1s. The activated C1s, in turn, cleaves COMPLEMENT C2 and COMPLEMENT C4 to form C4b2a (CLASSICAL C3 CONVERTASE).
A product of COMPLEMENT ACTIVATION cascade, regardless of the pathways, that forms transmembrane channels causing disruption of the target CELL MEMBRANE and cell lysis. It is formed by the sequential assembly of terminal complement components (COMPLEMENT C5B; COMPLEMENT C6; COMPLEMENT C7; COMPLEMENT C8; and COMPLEMENT C9) into the target membrane. The resultant C5b-8-poly-C9 is the "membrane attack complex" or MAC.
A 80-kDa subcomponent of complement C1, existing as a SERINE PROTEASE proenzyme in the intact complement C1 complex. When COMPLEMENT C1Q is bound to antibodies, the changed tertiary structure causes autolytic activation of complement C1r which is cleaved into two chains, A (heavy) and B (light, the serine protease), connected by disulfide bonds. The activated C1r serine protease, in turn, activates COMPLEMENT C1S proenzyme by cleaving the Arg426-Ile427 bond. No fragment is released when either C1r or C1s is cleaved.
A membrane or barrier with micrometer sized pores used for separation purification processes.
A 93-kDa serum glycoprotein encoded by C7 gene. It is a polypeptide chain with 28 disulfide bridges. In the formation of MEMBRANE ATTACK COMPLEX; C7 is the next component to bind the C5b-6 complex forming a trimolecular complex C5b-7 which is lipophilic, resembles an integral membrane protein, and serves as an anchor for the late complement components, C8 and C9.
Complement activation initiated by the binding of COMPLEMENT C1 to ANTIGEN-ANTIBODY COMPLEXES at the COMPLEMENT C1Q subunit. This leads to the sequential activation of COMPLEMENT C1R and COMPLEMENT C1S subunits. Activated C1s cleaves COMPLEMENT C4 and COMPLEMENT C2 forming the membrane-bound classical C3 CONVERTASE (C4B2A) and the subsequent C5 CONVERTASE (C4B2A3B) leading to cleavage of COMPLEMENT C5 and the assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX.
Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.
A 150-kDa serum glycoprotein composed of three subunits with each encoded by a different gene (C8A; C8B; and C8G). This heterotrimer contains a disulfide-linked C8alpha-C8gamma heterodimer and a noncovalently associated C8beta chain. C8 is the next component to bind the C5-7 complex forming C5b-8 that binds COMPLEMENT C9 and acts as a catalyst in the polymerization of C9.
The first complement component to act in the activation of CLASSICAL COMPLEMENT PATHWAY. It is a calcium-dependent trimolecular complex made up of three subcomponents: COMPLEMENT C1Q; COMPLEMENT C1R; and COMPLEMENT C1S at 1:2:2 ratios. When the intact C1 binds to at least two antibodies (involving C1q), C1r and C1s are sequentially activated, leading to subsequent steps in the cascade of COMPLEMENT ACTIVATION.
An important soluble regulator of the alternative pathway of complement activation (COMPLEMENT ACTIVATION PATHWAY, ALTERNATIVE). It is a 139-kDa glycoprotein expressed by the liver and secreted into the blood. It binds to COMPLEMENT C3B and makes iC3b (inactivated complement 3b) susceptible to cleavage by COMPLEMENT FACTOR I. Complement factor H also inhibits the association of C3b with COMPLEMENT FACTOR B to form the C3bB proenzyme, and promotes the dissociation of Bb from the C3bBb complex (COMPLEMENT C3 CONVERTASE, ALTERNATIVE PATHWAY).
Serum peptides derived from certain cleaved COMPLEMENT PROTEINS during COMPLEMENT ACTIVATION. They induce smooth MUSCLE CONTRACTION; mast cell HISTAMINE RELEASE; PLATELET AGGREGATION; and act as mediators of the local inflammatory process. The order of anaphylatoxin activity from the strongest to the weakest is C5a, C3a, C4a, and C5a des-arginine.
Molecular sites on or in some B-lymphocytes and macrophages that recognize and combine with COMPLEMENT C3B. The primary structure of these receptors reveal that they contain transmembrane and cytoplasmic domains, with their extracellular portion composed entirely of thirty short consensus repeats each having 60 to 70 amino acids.
The larger fragment generated from the cleavage of C5 by C5 CONVERTASE that yields COMPLEMENT C5A and C5b (beta chain + alpha' chain, the residual alpha chain, bound by disulfide bond). C5b remains bound to the membrane and initiates the spontaneous assembly of the late complement components to form C5b-8-poly-C9, the MEMBRANE ATTACK COMPLEX.
The COOH-terminal fragment of COMPLEMENT 2, released by the action of activated COMPLEMENT C1S. It is a SERINE PROTEASE. C2a combines with COMPLEMENT C4B to form C4b2a (CLASSICAL PATHWAY C3 CONVERTASE) and subsequent C4b2a3b (CLASSICAL PATHWAY C5 CONVERTASE).
A G-protein-coupled receptor that signals an increase in intracellular calcium in response to the potent ANAPHYLATOXIN peptide COMPLEMENT C5A.
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
Compounds that negatively regulate the cascade process of COMPLEMENT ACTIVATION. Uncontrolled complement activation and resulting cell lysis is potentially dangerous for the host.
A screening assay for circulating COMPLEMENT PROTEINS. Diluted SERUM samples are added to antibody-coated ERYTHROCYTES and the percentage of cell lysis is measured. The values are expressed by the so called CH50, in HEMOLYTIC COMPLEMENT units per milliliter, which is the dilution of serum required to lyse 50 percent of the erythrocytes in the assay.
Molecular sites on or in B-lymphocytes, follicular dendritic cells, lymphoid cells, and epithelial cells that recognize and combine with COMPLEMENT C3D. Human complement receptor 2 (CR2) serves as a receptor for both C3dg and the gp350/220 glycoprotein of HERPESVIRUS 4, HUMAN, and binds the monoclonal antibody OKB7, which blocks binding of both ligands to the receptor.
Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualized by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (hemolysin) requiring complement for its completion (stage 2). Failure of the red cells to lyse indicates that a specific antigen-antibody reaction has taken place in stage 1. If red cells lyse, free complement is present indicating no antigen-antibody reaction occurred in stage 1.
A serum protein which is important in the ALTERNATIVE COMPLEMENT ACTIVATION PATHWAY. This enzyme cleaves the COMPLEMENT C3B-bound COMPLEMENT FACTOR B to form C3bBb which is ALTERNATIVE PATHWAY C3 CONVERTASE.
The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes IMMUNE COMPLEX DISEASES.
A plasma serine proteinase that cleaves the alpha-chains of C3b and C4b in the presence of the cofactors COMPLEMENT FACTOR H and C4-binding protein, respectively. It is a 66-kDa glycoprotein that converts C3b to inactivated C3b (iC3b) followed by the release of two fragments, C3c (150-kDa) and C3dg (41-kDa). It was formerly called KAF, C3bINF, or enzyme 3b inactivator.
A serum protein that regulates the CLASSICAL COMPLEMENT ACTIVATION PATHWAY. It binds as a cofactor to COMPLEMENT FACTOR I which then hydrolyzes the COMPLEMENT C4B in the CLASSICAL PATHWAY C3 CONVERTASE (C4bC2a).
GPI-linked membrane proteins broadly distributed among hematopoietic and non-hematopoietic cells. CD55 prevents the assembly of C3 CONVERTASE or accelerates the disassembly of preformed convertase, thus blocking the formation of the membrane attack complex.
Important enzymes in the CLASSICAL COMPLEMENT ACTIVATION PATHWAY. They cleave COMPLEMENT C3 and COMPLEMENT C5.
The N-terminal fragment of COMPLEMENT 2, released by the action of activated COMPLEMENT C1S.
Small glycoproteins found on both hematopoietic and non-hematopoietic cells. CD59 restricts the cytolytic activity of homologous complement by binding to C8 and C9 and blocking the assembly of the membrane attack complex. (From Barclay et al., The Leukocyte Antigen FactsBook, 1993, p234)
A metallocarboxypeptidase that removes C-terminal basic amino acid from peptides and proteins, with preference shown for lysine over arginine. It is a plasma zinc enzyme that inactivates bradykinin and anaphylatoxins.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
The rate dynamics in chemical or physical systems.
A technique that combines protein electrophoresis and double immunodiffusion. In this procedure proteins are first separated by gel electrophoresis (usually agarose), then made visible by immunodiffusion of specific antibodies. A distinct elliptical precipitin arc results for each protein detectable by the antisera.
A major cytochrome P-450 enzyme which is inducible by PHENOBARBITAL in both the LIVER and SMALL INTESTINE. It is active in the metabolism of compounds like pentoxyresorufin, TESTOSTERONE, and ANDROSTENEDIONE. This enzyme, encoded by CYP2B1 gene, also mediates the activation of CYCLOPHOSPHAMIDE and IFOSFAMIDE to MUTAGENS.
The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).
Venoms from snakes of the genus Naja (family Elapidae). They contain many specific proteins that have cytotoxic, hemolytic, neurotoxic, and other properties. Like other elapid venoms, they are rich in enzymes. They include cobramines and cobralysins.
An adrenal microsomal cytochrome P450 enzyme that catalyzes the 21-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP21 gene, converts progesterones to precursors of adrenal steroid hormones (CORTICOSTERONE; HYDROCORTISONE). Defects in CYP21 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).
Mercuriphenols substituted with one or more chlorine atoms and one or more nitro groups. Some of these are sulfhydryl reagents which act as chromophoric probes in enzymes and other proteins.
Important enzymes in the ALTERNATIVE COMPLEMENT ACTIVATION PATHWAY. They cleave COMPLEMENT C3 and COMPLEMENT C5.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Swelling involving the deep DERMIS, subcutaneous, or submucosal tissues, representing localized EDEMA. Angioedema often occurs in the face, lips, tongue, and larynx.
An endogenous 105-kDa plasma glycoprotein produced primarily by the LIVER and MONOCYTES. It inhibits a broad spectrum of proteases, including the COMPLEMENT C1R and the COMPLEMENT C1S proteases of the CLASSICAL COMPLEMENT PATHWAY, and the MANNOSE-BINDING PROTEIN-ASSOCIATED SERINE PROTEASES. C1-INH-deficient individuals suffer from HEREDITARY ANGIOEDEMA TYPES I AND II.

Regulation of complement activation by C-reactive protein: targeting the complement inhibitory activity of factor H by an interaction with short consensus repeat domains 7 and 8-11. (1/204)

C-reactive protein (CRP) is a major acute phase protein whose functions are not totally clear. In this study, we examined the interaction of CRP with factor H (FH), a key regulator of the alternative pathway (AP) of complement. Using the surface plasmon resonance technique and a panel of recombinantly expressed FH constructs, we observed that CRP binds to two closely located regions on short consensus repeat (SCR) domains 7 and 8-11 of FH. Also FH-like protein 1 (FHL-1), an alternatively spliced product of the FH gene, bound to CRP with its most C-terminal domain (SCR 7). The binding reactions were calcium-dependent and partially inhibited by heparin. In accordance with the finding that CRP binding sites on FH were distinct from the C3b binding sites, CRP preserved the ability of FH to promote factor I-mediated cleavage of C3b. We propose that the function of CRP is to target functionally active FH and FHL-1 to injured self tissues. Thereby, CRP could restrict excessive complement attack in tissues while allowing a temporarily enhanced AP activity against invading microbes in blood.  (+info)

Complement activation in patients with systemic lupus erythematosus without nephritis. (2/204)

OBJECTIVE: To study the association between disease activity and complement activation prospectively in patients with systemic lupus erythematosus (SLE). PATIENTS AND METHODS: Twenty-one SLE patients were examined monthly for 1 yr. Disease activity, autoantibodies, conventional complement tests and the following complement activation products were investigated: C1rs-C1inh complexes, C4bc, Bb, C3a, C3bc, C5a and the terminal SC5b-9 complement complex (TCC). RESULTS: Modest variation in disease activity was noted. None of the patients had nephritis. Flare was observed at 27 visits. Four patients had anti-C1q antibodies in conjunction with modestly low C1q concentrations. The complement parameters were rather constant during the observation period. Slightly to moderately decreased C4 (0.05-0.10 g/l) was found in 10 patients and severely decreased C4 (<0.05 g/l) in seven patients. Decreased C4 was not associated with increased complement activation. Complement activation products were either normal or slightly elevated. TCC was the only activation product correlating significantly with score for disease activity at flare. None of the variables tested predicted flares. CONCLUSION: Complement tests are of limited importance in routine examination of SLE without nephritis, although TCC is suggested to be one of the most sensitive markers for disease activity.  (+info)

Different regulation of factor H and FHL-1/reconectin by inflammatory mediators and expression of the two proteins in rheumatoid arthritis (RA). (3/204)

Factor H and the FHL-1/reconectin protein are two human plasma proteins that act as important regulators of the alternative complement pathway. Each protein is encoded by a unique transcript, but both mRNAs are derived from the factor H gene by means of alternative processing. In order to address potential functional differences between the two proteins we analysed their expression in hepatic and non-hepatic cells and studied their regulation by inflammatory mediators. We demonstrate that factor H and FHL-1/reconectin transcripts which are regulated by the same gene promoter and are initiated at the same transcription start site are differently expressed. Expression of the molecules is induced and regulated by the inflammatory mediators interferon-gamma (IFN-gamma) and the anti-inflammatory glucocorticoid dexamethasone. Both factor H and FHL-1/reconectin are expressed and secreted by synovial fibroblasts and are present in synovial fluid derived from patients suffering from rheumatoid or reactive arthritis. The local synthesis in synovial fibroblasts and their induction by IFN-gamma and dexamethasone, but not by tumour necrosis factor-alpha, suggests for each of the two complement regulators a protective role in RA.  (+info)

Structure-guided identification of C3d residues essential for its binding to complement receptor 2 (CD21). (4/204)

A vital role for complement in adaptive humoral immunity is now beyond dispute. The crucial interaction is that between B cell and follicular dendritic cell-resident complement receptor 2 (CR2, CD21) and its Ag-associated ligands iC3b and C3dg, where the latter have been deposited as a result of classical pathway activation. Despite the obvious importance of this interaction, the location of a CR2 binding site within C3d, a proteolytic limit fragment of C3dg retaining CR2 binding activity, has not been firmly established. The recently determined x-ray structure of human C3d suggested a candidate site that was remote from the site of covalent attachment to Ag and consisted of an acidic residue-lined depression, which accordingly displays a significant electronegative surface potential. These attributes were consistent with the known ionic strength dependence of the CR2-C3d interaction and with the fact that a significant electropositive surface was apparent in a modeled structure of the C3d-binding domains of CR2. Therefore, we have performed an alanine scan of all of the residues within and immediately adjacent to the acidic pocket in C3d. By testing the mutant iC3b molecules for their ability to bind CR2, we have identified two separate clusters of residues on opposite sides of the acidic pocket, specifically E37/E39 and E160/D163/I164/E166, as being important CR2-contacting residues in C3d. Within the second cluster even single mutations cause near total loss of CR2 binding activity. Consistent with the proposed oppositely charged nature of the interface, we have also found that removal of a positive charge immediately adjacent to the acidic pocket (mutant K162A) results in a 2-fold enhancement in CR2 binding activity.  (+info)

Cooperation between decay-accelerating factor and membrane cofactor protein in protecting cells from autologous complement attack. (5/204)

Decay-accelerating factor (DAF or CD55) and membrane cofactor protein (MCP or CD46) function intrinsically in the membranes of self cells to prevent activation of autologous complement on their surfaces. How these two regulatory proteins cooperate on self-cell surfaces to inhibit autologous complement attack is unknown. In this study, a GPI-anchored form of MCP was generated. The ability of this recombinant protein and that of naturally GPI-anchored DAF to incorporate into cell membranes then was exploited to examine the combined functions of DAF and MCP in regulating complement intermediates assembled from purified alternative pathway components on rabbit erythrocytes. Quantitative studies with complement-coated rabbit erythrocyte intermediates constituted with each protein individually or the two proteins together demonstrated that DAF and MCP synergize the actions of each other in preventing C3b deposition on the cell surface. Further analyses showed that MCP's ability to catalyze the factor I-mediated cleavage of cell-bound C3b is inhibited in the presence of factors B and D and is restored when DAF is incorporated into the cells. Thus, the activities of DAF and MCP, when present together, are greater than the sum of the two proteins individually, and DAF is required for MCP to catalyze the cleavage of cell-bound C3b in the presence of excess factors B and D. These data are relevant to xenotransplantation, pharmacological inhibition of complement in inflammatory diseases, and evasion of tumor cells from humoral immune responses.  (+info)

The complement regulator factor H binds to the surface protein OspE of Borrelia burgdorferi. (6/204)

Spirochete bacteria of the Borrelia burgdorferi sensu lato complex cause Lyme borreliosis. The three pathogenic subspecies Borrelia garinii, Borrelia afzelii, and Borrelia burgdorferi sensu stricto differ in their disease profiles and susceptibility to complement lysis. We investigated whether complement resistance of Borreliae could be due to acquisition of the main soluble inhibitors of the alternative complement pathway, factor H and the factor H-like protein 1. When exposed to nonimmune EDTA-plasma, the serum-resistant B. afzelii and B. burgdorferi sensu stricto strains bound factor H/factor H-like protein 1 to their surfaces. Assays with radiolabeled proteins showed that factor H bound strongly to the B. burgdorferi sensu stricto strain. To identify factor H ligands on the borrelial surface, we analyzed a panel of outer surface proteins of B. burgdorferi sensu stricto with the surface plasmon resonance technique. The outer surface lipoprotein OspE was identified as a specific ligand for factor H. Using recombinant constructs of factor H, the binding site for OspE was localized to the C-terminal short consensus repeat domains 15-20. Specific binding of factor H to B. burgdorferi sensu stricto OspE may help the pathogen to evade complement attack and phagocytosis.  (+info)

Complement evasion by Borrelia burgdorferi: serum-resistant strains promote C3b inactivation. (7/204)

The most characteristic features of the Lyme disease pathogens, the Borrelia burgdorferi sensu lato (s.l.) group, are their ability to invade tissues and to circumvent the immune defenses of the host for extended periods of time, despite elevated levels of borrelia-specific antibodies in serum and other body fluids. Our aim in the present study was to determine whether B. burgdorferi is able to interfere with complement (C) at the level of C3 by accelerating C3b inactivation and thus to inhibit the amplification of the C cascade. Strains belonging to different genospecies (Borrelia garinii, B. burgdorferi sensu stricto, and Borrelia afzelii) were compared for their sensitivities to normal human serum and abilities to promote factor I-mediated C3b degradation. B. burgdorferi sensu stricto and B. afzelii strains were found to be serum resistant. When the spirochetes were incubated with radiolabeled C3b, factor I-mediated degradation of C3b was observed in the presence of C-resistant B. afzelii (n = 3) and B. burgdorferi sensu stricto (n = 1) strains but not in the presence of C-sensitive B. garinii (n = 7) strains or control bacteria (Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis). Immunoblotting and radioligand binding analyses showed that the C-resistant strains had the capacity to acquire the C inhibitors factor H and factor H-like protein 1 (FHL-1) from growth medium and human serum. A novel surface protein with an apparent molecular mass of 35 kDa was found to preferentially bind to the N terminus region of factor H. Thus, the serum-resistant B. burgdorferi s.l. strains can circumvent C attack by binding the C inhibitors factor H and FHL-1 to their surfaces and promoting factor I-mediated C3b degradation.  (+info)

Relative importance of C3b inactivator and beta 1H globulin in the modulation of the properdin amplification loop in systemic lupus erythematosus. (8/204)

Serum concentrations of C4, C3, factor B (B), properdin (P), C3b inactivator (C3bINA) and beta 1H globulin have been measured by radial immunodiffusion in sixty-two samples from thirteen patients with systemic lupus erythematosus (SLE). Significant reductions in the mean serum concentrations of C4 (classical pathway) B and P (alternative pathway) and C3 were found. In addition, the mean level of the control protein beta 1H, but not C3bINA, was reduced. Sera from thirteen patients taking during disease exacerbation (low C3) showed significantly lower levels of both C3bINA and beta 1H than sera taken from the same thirteen patients during disease remission (high C3). Serum concentrations of C3bINA correlated with B (P less than 0.005) but not C4, C3 or P, whereas levels of beta 1H correlated with C4 (P less than 0.01), B (P less than 0.005) and properdin (P less than 0.01). Serial measurements of the serum concentrations of C3bINA and beta 1H showed that levels of these protein fell during exacerbation, and such falls were more closely associated with diseases in the serum levels of the alternative pathways proteins than C4. It is concluded from these observations that serum concentrations of the control proteins C3bINA and beta 1H, especially the latter, control the extent of turnover of the alternative pathway in SLE. Metabolic studies are required to determine the causes of the decreased serum concentrations of these control proteins.  (+info)

Complement C3b inactivator proteins, also known as complement regulators or decay-accelerating factor (DAF), are a group of proteins that play a crucial role in regulating the complement system. The complement system is a part of the immune system that helps to eliminate pathogens and damaged cells from the body.

The complement C3b inactivator proteins include two main types: complement receptor 1 (CR1) and decay-accelerating factor (DAF). These proteins work by regulating the formation of the membrane attack complex (MAC), a protein structure that forms pores in the cell membrane, leading to cell lysis.

Complement C3b inactivator proteins bind to C3b and C4b components of the complement system, preventing them from forming the MAC. By doing so, they help to prevent excessive activation of the complement system, which can damage healthy cells and tissues.

Deficiencies or dysfunction of complement C3b inactivator proteins have been associated with several diseases, including autoimmune disorders, inflammatory diseases, and infectious diseases. Therefore, understanding the role of these proteins in regulating the complement system is essential for developing new therapies to treat these conditions.

Complement C3 is a protein that plays a central role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Complement C3 can be activated through three different pathways: the classical pathway, the lectin pathway, and the alternative pathway. Once activated, it breaks down into two fragments, C3a and C3b.

C3a is an anaphylatoxin that helps to recruit immune cells to the site of infection or injury, while C3b plays a role in opsonization, which is the process of coating pathogens or damaged cells with proteins to make them more recognizable to the immune system. Additionally, C3b can also activate the membrane attack complex (MAC), which forms a pore in the membrane of target cells leading to their lysis or destruction.

In summary, Complement C3 is an important protein in the complement system that helps to identify and eliminate pathogens and damaged cells from the body through various mechanisms.

Complement C4 is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Complement C4 is involved in the early stages of the complement activation cascade, where it helps to identify and tag foreign or abnormal cells for destruction by other components of the immune system.

Specifically, Complement C4 can be cleaved into two smaller proteins, C4a and C4b, during the complement activation process. C4b then binds to the surface of the target cell and helps to initiate the formation of the membrane attack complex (MAC), which creates a pore in the cell membrane and leads to lysis or destruction of the target cell.

Deficiencies or mutations in the Complement C4 gene can lead to various immune disorders, including certain forms of autoimmune diseases and susceptibility to certain infections.

Complement inactivator proteins are a group of regulatory proteins that help to control and limit the activation of the complement system, which is a part of the immune system. The complement system is a complex series of biochemical reactions that help to eliminate pathogens and damaged cells from the body. However, if not properly regulated, the complement system can also cause damage to healthy tissues and contribute to the development of various diseases.

Complement inactivator proteins work by inhibiting specific components of the complement system, preventing them from activating and causing an immune response. Some examples of complement inactivator proteins include:

1. C1 inhibitor (C1INH): This protein regulates the activation of the classical pathway of the complement system by inhibiting the C1 complex, which is a group of proteins that initiate this pathway.
2. Decay-accelerating factor (DAF or CD55): This protein regulates the activation of both the classical and alternative pathways of the complement system by accelerating the decay of the C3/C5 convertases, which are enzymes that activate the complement components C3 and C5.
3. Membrane cofactor protein (MCP or CD46): This protein regulates the activation of the alternative pathway of the complement system by serving as a cofactor for the cleavage and inactivation of C3b, a component of the C3 convertase.
4. Factor H: This protein also regulates the activation of the alternative pathway of the complement system by acting as a cofactor for the cleavage and inactivation of C3b, and by preventing the formation of the C3 convertase.

Deficiencies or dysfunction of complement inactivator proteins can lead to various diseases, including hereditary angioedema (C1INH deficiency), atypical hemolytic uremic syndrome (factor H deficiency or dysfunction), and age-related macular degeneration (complement component overactivation).

Complement C1 Inactivator proteins are a part of the complement system, which is a group of proteins in the blood that play a crucial role in the body's immune defense system. Specifically, Complement C1 Inactivator proteins are responsible for regulating the activation of the first component of the complement system, C1.

The complement system is activated in response to the presence of foreign substances such as bacteria or viruses in the body. The activation of C1 leads to a cascade of reactions that result in the destruction of the foreign substance. However, if this process is not properly regulated, it can lead to damage to the body's own cells and tissues.

Complement C1 Inactivator proteins help to prevent this by regulating the activation of C1. They do this by binding to and inhibiting the activity of C1, preventing it from initiating the complement cascade. A deficiency in Complement C1 Inactivator proteins can lead to a condition called hereditary angioedema, which is characterized by recurrent episodes of swelling in various parts of the body.

Properdin is defined as a positive regulatory protein in the complement system, which is a part of the immune system. It plays a crucial role in the alternative pathway of complement activation. Properdin stabilizes the C3 convertase (C3bBb), preventing its decay and increasing the efficiency of the alternative pathway. This results in the production of the membrane attack complex, which leads to the lysis of foreign cells or pathogens. Deficiencies in properdin can lead to an increased susceptibility to bacterial infections.

Complement C3b is a protein fragment that plays a crucial role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. C3b is generated during the activation of the complement system, particularly via the classical, lectin, and alternative pathways.

Once formed, C3b can bind covalently to the surface of microbes or other target particles, marking them for destruction by other components of the immune system. Additionally, C3b can interact with other proteins in the complement system to generate the membrane attack complex (MAC), which forms pores in the membranes of targeted cells, leading to their lysis and removal.

In summary, Complement C3b is a vital protein fragment involved in the recognition, tagging, and elimination of pathogens and damaged cells during the immune response.

The complement system is a group of proteins found in the blood and on the surface of cells that when activated, work together to help eliminate pathogens such as bacteria, viruses, and fungi from the body. The proteins are normally inactive in the bloodstream. When they encounter an invading microorganism or foreign substance, a series of reactions take place leading to the activation of the complement system. Activation results in the production of effector molecules that can punch holes in the cell membranes of pathogens, recruit and activate immune cells, and help remove debris and dead cells from the body.

There are three main pathways that can lead to complement activation: the classical pathway, the lectin pathway, and the alternative pathway. Each pathway involves a series of proteins that work together in a cascade-like manner to amplify the response and generate effector molecules. The three main effector molecules produced by the complement system are C3b, C4b, and C5b. These molecules can bind to the surface of pathogens, marking them for destruction by other immune cells.

Complement proteins also play a role in the regulation of the immune response. They help to prevent excessive activation of the complement system, which could damage host tissues. Dysregulation of the complement system has been implicated in a number of diseases, including autoimmune disorders and inflammatory conditions.

In summary, Complement System Proteins are a group of proteins that play a crucial role in the immune response by helping to eliminate pathogens and regulate the immune response. They can be activated through three different pathways, leading to the production of effector molecules that mark pathogens for destruction. Dysregulation of the complement system has been linked to various diseases.

Complement activation is the process by which the complement system, a part of the immune system, is activated to help eliminate pathogens and damaged cells from the body. The complement system consists of a group of proteins that work together to recognize and destroy foreign substances.

Activation of the complement system can occur through three different pathways: the classical pathway, the lectin pathway, and the alternative pathway. Each pathway involves a series of proteolytic reactions that ultimately result in the formation of the membrane attack complex (MAC), which creates a pore in the membrane of the target cell, leading to its lysis and removal.

The classical pathway is typically activated by the binding of antibodies to antigens on the surface of a pathogen or damaged cell. The lectin pathway is activated by the recognition of specific carbohydrate structures on the surface of microorganisms. The alternative pathway can be spontaneously activated and serves as an amplification loop for both the classical and lectin pathways.

Complement activation plays a crucial role in the immune response, but uncontrolled or excessive activation can also lead to tissue damage and inflammation. Dysregulation of complement activation has been implicated in various diseases, including autoimmune disorders, inflammatory conditions, and neurodegenerative diseases.

Complement C4a is a protein fragment or cleavage product generated during the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens and damaged cells by marking them for destruction and direct lysis. Complement component 4 (C4) is one of the key proteins in this cascade, and it gets cleaved into C4a and C4b during the activation process.

C4a is a small anaphylatoxin with a molecular weight of approximately 9 kDa. It has chemotactic properties, meaning it can attract immune cells like neutrophils to the site of complement activation. Additionally, C4a can induce histamine release from mast cells and basophils, contributing to local inflammation. However, its precise physiological role in the immune response is not entirely clear, and dysregulation of C4a production has been implicated in several pathological conditions, such as autoimmune diseases and allergies.

Complement C2 is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. Specifically, C2 is a component of the classical complement pathway, which is activated by the binding of antibodies to antigens on the surface of foreign particles or cells.

When the classical pathway is activated, C2 is cleaved into two fragments: C2a and C2b. C2a then binds to C4b to form the C3 convertase (C4b2a), which cleaves C3 into C3a and C3b. C3b can then go on to form the membrane attack complex, which creates a pore in the membrane of the target cell, leading to its lysis.

In summary, Complement C2 is a protein that helps to activate the complement system and destroy foreign particles or cells through the formation of the C3 convertase and the membrane attack complex.

Complement C3-C5 convertases are proteins that play a crucial role in the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens and damaged cells from the body by marking them for destruction and attracting immune cells to the site of infection or injury.

The C3-C5 convertases are formed during the activation of the complement component 3 (C3) protein, which is a central player in the complement system. The formation of the C3-C5 convertase involves two main steps:

1. C3 convertase formation: In this step, a complex of proteins called the C3 convertase is formed by the cleavage of C3 into C3a and C3b fragments. This complex can then cleave additional C3 molecules into C3a and C3b fragments, amplifying the complement response.
2. C5 convertase formation: In this step, the C3b fragment from the C3 convertase binds to another protein called C4b2a, forming a new complex called the C5 convertase. The C5 convertase can then cleave the C5 protein into C5a and C5b fragments.

The C5b fragment goes on to form the membrane attack complex (MAC), which creates a pore in the membrane of the target cell, leading to its lysis or destruction. The C3a and C5a fragments are small proteins called anaphylatoxins that can cause inflammation and attract immune cells to the site of infection or injury.

Overall, the formation of Complement C3-C5 convertases is a critical step in the activation of the complement system and plays a key role in the body's defense against pathogens and damaged cells.

Complement Factor B is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. Specifically, Factor B is a component of the alternative pathway of the complement system, which provides a rapid and amplified response to microbial surfaces.

Factor B is cleaved by another protease called Factor D into two fragments, Ba and Bb. The formation of the C3 convertase (C3bBb) is essential for the activation of the alternative pathway. This complex can cleave and activate more C3 molecules, leading to a cascade of reactions that result in the formation of the membrane attack complex (MAC), which forms pores in the membranes of target cells, causing their lysis and elimination.

Deficiencies or mutations in Complement Factor B can lead to various complement-mediated diseases, such as atypical hemolytic uremic syndrome (aHUS) and age-related macular degeneration (AMD).

Complement C3a is a protein fragment that is generated during the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens and damaged cells from the body by marking them for destruction and attracting immune cells to the site of infection or injury.

C3a is produced when the third component of the complement system (C3) is cleaved into two smaller fragments, C3a and C3b, during the complement activation cascade. C3a is a potent anaphylatoxin, which means it can cause the release of histamine and other mediators from mast cells and basophils, leading to inflammation, increased vascular permeability, and smooth muscle contraction.

C3a also has chemotactic properties, meaning it can attract immune cells such as neutrophils and monocytes to the site of complement activation. Additionally, C3a can modulate the activity of various immune cells, including dendritic cells, T cells, and B cells, and play a role in the regulation of the adaptive immune response.

It's important to note that while C3a has important functions in the immune response, uncontrolled or excessive activation of the complement system can lead to tissue damage and inflammation, contributing to the pathogenesis of various diseases such as autoimmune disorders, inflammatory diseases, and allergies.

The alternative complement pathway is one of the three initiating pathways of the complement system, which is a part of the innate immune system that helps to clear pathogens and damaged cells from the body. The other two pathways are the classical and lectin pathways.

The alternative pathway is continuously activated at a low level, even in the absence of infection or injury, through the spontaneous cleavage of complement component C3 into C3a and C3b by the protease factor D in the presence of magnesium ions. The generated C3b can then bind covalently to nearby surfaces, including pathogens and host cells.

On self-surfaces, regulatory proteins like decay-accelerating factor (DAF) or complement receptor 1 (CR1) help to prevent the formation of the alternative pathway convertase and thus further activation of the complement system. However, on foreign surfaces, the C3b can recruit more complement components, forming a complex called the alternative pathway convertase (C3bBb), which cleaves additional C3 molecules into C3a and C3b.

The generated C3b can then bind to the surface and participate in the formation of the membrane attack complex (MAC), leading to the lysis of the target cell. The alternative pathway plays a crucial role in the defense against gram-negative bacteria, fungi, and parasites, as well as in the clearance of immune complexes and apoptotic cells. Dysregulation of the alternative complement pathway has been implicated in several diseases, including autoimmune disorders and atypical hemolytic uremic syndrome (aHUS).

Complement C1q is a protein that is part of the complement system, which is a group of proteins in the blood that help to eliminate pathogens and damaged cells from the body. C1q is the first component of the classical complement pathway, which is activated by the binding of C1q to antibodies that are attached to the surface of a pathogen or damaged cell.

C1q is composed of six identical polypeptide chains, each containing a collagen-like region and a globular head region. The globular heads can bind to various structures, including the Fc regions of certain antibodies, immune complexes, and some types of cells. When C1q binds to an activating surface, it triggers a series of proteolytic reactions that lead to the activation of other complement components and the formation of the membrane attack complex (MAC), which can punch holes in the membranes of pathogens or damaged cells, leading to their destruction.

In addition to its role in the immune system, C1q has also been found to have roles in various physiological processes, including tissue remodeling, angiogenesis, and the clearance of apoptotic cells. Dysregulation of the complement system, including abnormalities in C1q function, has been implicated in a variety of diseases, including autoimmune disorders, inflammatory diseases, and neurodegenerative conditions.

Complement C5 is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. The complement system is a complex series of biochemical reactions that help to identify and destroy foreign substances, such as bacteria and viruses.

Complement C5 is one of several proteins in the complement system that are activated in a cascading manner in response to an activating event, such as the binding of an antibody to a pathogen. Once activated, Complement C5 can be cleaved into two smaller proteins, C5a and C5b.

C5a is a powerful anaphylatoxin, which means it can cause the release of histamine from mast cells and basophils, leading to inflammation and increased vascular permeability. It also acts as a chemoattractant, drawing immune cells to the site of infection or injury.

C5b, on the other hand, plays a role in the formation of the membrane attack complex (MAC), which is a protein structure that can punch holes in the membranes of pathogens, leading to their lysis and destruction.

Overall, Complement C5 is an important component of the immune system's response to infection and injury, helping to eliminate pathogens and damaged cells from the body.

Complement C5a is a protein fragment that is generated during the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens and damaged cells from the body by tagging them for destruction and attracting immune cells to the site of infection or injury.

C5a is formed when the fifth component of the complement system (C5) is cleaved into two smaller fragments, C5a and C5b, during the complement activation cascade. C5a is a potent pro-inflammatory mediator that can attract and activate various immune cells, such as neutrophils, monocytes, and eosinophils, to the site of infection or injury. It can also increase vascular permeability, promote the release of histamine, and induce the production of reactive oxygen species, all of which contribute to the inflammatory response.

However, excessive or uncontrolled activation of the complement system and generation of C5a can lead to tissue damage and inflammation, contributing to the pathogenesis of various diseases, such as sepsis, acute respiratory distress syndrome (ARDS), and autoimmune disorders. Therefore, targeting C5a or its receptors has been explored as a potential therapeutic strategy for these conditions.

Complement C4b is a protein fragment that is formed during the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens and damaged cells from the body by tagging them for destruction and attracting immune cells to the site of infection or injury.

C4b is generated when the C4 protein is cleaved into two smaller fragments, C4a and C4b, during the activation of the classical or lectin pathways of the complement system. C4b then binds covalently to the surface of the target cell or pathogen, forming a complex with other complement proteins that can create a membrane attack complex (MAC) and cause cell lysis.

C4b can also act as an opsonin, coating the surface of the target cell or pathogen and making it easier for immune cells to recognize and phagocytose them. Additionally, C4b can activate the alternative pathway of the complement system, leading to further amplification of the complement response.

Complement activating enzymes are proteins that play a crucial role in the activation of the complement system, which is a part of the immune system. The complement system is a complex series of biochemical reactions that help to eliminate pathogens and damaged cells from the body.

There are several types of complement activating enzymes, including:

1. Classical pathway activators: These include the C1, C4, and C2 components of the complement system. When activated, they trigger a series of reactions that lead to the formation of the membrane attack complex (MAC), which creates a pore in the membrane of the target cell, leading to its lysis.
2. Alternative pathway activators: These include factors B, D, and P. They are constantly active at low levels and can be activated by surfaces that are not normally found in the body, such as bacterial cell walls. Once activated, they also trigger the formation of the MAC.
3. Lectin pathway activators: These include mannose-binding lectin (MBL) and ficolins. They bind to carbohydrates on the surface of microbes and activate the complement system through the MBL-associated serine proteases (MASPs).

Overall, complement activating enzymes play a critical role in the immune response by helping to identify and eliminate pathogens and damaged cells from the body.

Beta-globulins are a group of proteins found in the beta region of a serum protein electrophoresis, which is a laboratory test used to separate and identify different types of proteins in the blood. This group includes several important proteins such as:

1. Beta-lipoproteins: These are responsible for transporting fat molecules, including cholesterol, throughout the body.
2. Transferrin: A protein that binds and transports iron in the blood.
3. Complement components: These proteins play a crucial role in the immune system's response to infection and inflammation.
4. Beta-2 microglobulin: A protein involved in the functioning of the immune system, elevated levels of which can be found in various conditions such as kidney disease and autoimmune disorders.
5. Hemopexin: A protein that binds and transports heme (a component of hemoglobin) in the blood.

It is important to note that any significant increase or decrease in beta-globulins can indicate an underlying medical condition, such as liver disease, kidney disease, or an autoimmune disorder. Therefore, abnormal results should be further evaluated by a healthcare professional for proper diagnosis and treatment.

Complement C6 is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. Specifically, C6 is a component of the membrane attack complex (MAC), which is a group of proteins that work together to form a pore in the membrane of target cells, leading to their lysis or destruction.

The complement system is activated through several different pathways, including the classical pathway, the lectin pathway, and the alternative pathway. Once activated, these pathways converge at the level of C3, which is cleaved into C3a and C3b fragments. C3b can then bind to the surface of target cells and initiate the formation of the MAC.

C6 is one of several proteins that are required for the formation of the MAC. When C6 binds to C7, it undergoes a conformational change that allows it to interact with C8 and form a stable complex. This complex then recruits additional C9 molecules, which polymerize to form the pore in the target cell membrane.

Deficiencies in complement components, including C6, can lead to increased susceptibility to certain types of infections, as well as autoimmune disorders and other medical conditions.

Complement C3c is a protein component of the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Complement C3c is formed when the third component of the complement system (C3) is cleaved into two smaller proteins, C3a and C3b, during the complement activation process.

C3b can then be further cleaved into C3c and C3dg. C3c is a stable fragment that remains in the circulation and can be measured in blood tests as a marker of complement activation. It plays a role in the opsonization of pathogens, which means it coats them to make them more recognizable to immune cells, and helps to initiate the membrane attack complex (MAC), which forms a pore in the cell membrane of pathogens leading to their lysis or destruction.

Abnormal levels of C3c may indicate an underlying inflammatory or immune-mediated condition, such as infection, autoimmune disease, or cancer.

Complement C3d is a protein fragment that is formed during the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens such as bacteria and viruses from the body by tagging them for destruction and attracting immune cells to the site of infection.

C3d is a cleavage product of complement component C3, which is one of the central proteins in the complement system. When C3 is activated, it is cleaved into two fragments: C3a and C3b. C3b can then be further cleaved into C3d and C3c.

C3d plays a role in the activation of the immune system by helping to link the complement system with the adaptive immune response. It does this by binding to receptors on B cells, which are a type of white blood cell that produces antibodies. This interaction can help to stimulate the production of antibodies and enhance the immune response to pathogens.

C3d has also been implicated in the development of certain autoimmune diseases, as it can contribute to the formation of immune complexes that can cause tissue damage.

Serum globulins are a group of proteins present in the liquid portion of blood, known as serum. They are produced by the immune system in response to foreign substances such as bacteria, viruses, and allergens. Serum globulins include several types of immunoglobulins (antibodies), complement components, and other proteins involved in the immune response.

The serum globulin level is often measured as part of a complete blood count (CBC) or a protein electrophoresis test. An elevated serum globulin level may indicate an ongoing infection, inflammation, or an autoimmune disorder. Conversely, a decreased level may suggest a liver or kidney disease, or a malnutrition condition. It is important to note that the interpretation of serum globulin levels should be done in conjunction with other laboratory and clinical findings.

Complement C9 is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. Specifically, C9 is one of the components of the membrane attack complex (MAC), which is a protein structure that forms pores in the membranes of target cells, leading to their lysis or destruction.

When activated, C9 polymerizes and inserts itself into the cell membrane, forming a transmembrane pore that disrupts the membrane's integrity and causes the cell to lyse. This process is an essential part of the complement system's ability to destroy pathogens and clear damaged cells from the body.

Defects in the C9 gene can lead to a rare genetic disorder called complement component 9 deficiency, which is characterized by recurrent bacterial infections and immune complex-mediated diseases. Additionally, mutations in the C9 gene have been associated with an increased risk of age-related macular degeneration (AMD), a leading cause of blindness in older adults.

Complement receptors are proteins found on the surface of various cells in the human body, including immune cells and some non-immune cells. They play a crucial role in the complement system, which is a part of the innate immune response that helps to eliminate pathogens and damaged cells from the body. Complement receptors bind to complement proteins or fragments that are generated during the activation of the complement system. This binding triggers various intracellular signaling events that can lead to diverse cellular responses, such as phagocytosis, inflammation, and immune regulation.

There are several types of complement receptors, including:

1. CR1 (CD35): A receptor found on erythrocytes, B cells, neutrophils, monocytes, macrophages, and glomerular podocytes. It functions in the clearance of immune complexes and regulates complement activation.
2. CR2 (CD21): Expressed mainly on B cells and follicular dendritic cells. It facilitates antigen presentation, B-cell activation, and immune regulation.
3. CR3 (CD11b/CD18, Mac-1): Present on neutrophils, monocytes, macrophages, and some T cells. It mediates cell adhesion, phagocytosis, and intracellular signaling.
4. CR4 (CD11c/CD18, p150,95): Expressed on neutrophils, monocytes, macrophages, and dendritic cells. It is involved in cell adhesion, phagocytosis, and intracellular signaling.
5. C5aR (CD88): Found on various immune cells, including neutrophils, monocytes, macrophages, mast cells, eosinophils, and dendritic cells. It binds to the complement protein C5a and mediates chemotaxis, degranulation, and inflammation.
6. C5L2 (GPR77): Present on various cell types, including immune cells. Its function is not well understood but may involve regulating C5a-mediated responses or acting as a receptor for other ligands.

These receptors play crucial roles in the immune response and inflammation by mediating various functions such as chemotaxis, phagocytosis, cell adhesion, and intracellular signaling. Dysregulation of these receptors has been implicated in several diseases, including autoimmune disorders, infections, and cancer.

Hemolysis is the destruction or breakdown of red blood cells, resulting in the release of hemoglobin into the surrounding fluid (plasma). This process can occur due to various reasons such as chemical agents, infections, autoimmune disorders, mechanical trauma, or genetic abnormalities. Hemolysis may lead to anemia and jaundice, among other complications. It is essential to monitor hemolysis levels in patients undergoing medical treatments that might cause this condition.

Complement C1s is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Specifically, C1s is a component of the first protein complex in the classical complement pathway, called C1.

C1 is composed of three subunits: C1q, C1r, and C1s. When C1 encounters an activating surface, such as an antibody-antigen complex or certain types of viruses and bacteria, it undergoes a conformational change that allows C1r to cleave and activate C1s. Activated C1s then goes on to cleave and activate other components in the complement pathway, leading to the generation of the membrane attack complex (MAC) and subsequent lysis of the target cell.

Deficiencies or mutations in the genes encoding complement proteins, including C1s, can lead to various immune disorders and increased susceptibility to infections.

The Complement Membrane Attack Complex (MAC), also known as the Terminal Complement Complex (TCC), is a protein structure that forms in the final stages of the complement system's immune response. The complement system is a part of the innate immune system that helps to eliminate pathogens and damaged cells from the body.

The MAC is composed of several proteins, including C5b, C6, C7, C8, and multiple subunits of C9, which assemble on the surface of target cells. The formation of the MAC creates a pore-like structure in the cell membrane, leading to disruption of the membrane's integrity and ultimately causing cell lysis or damage.

The MAC plays an important role in the immune response by helping to eliminate pathogens that have evaded other immune defenses. However, uncontrolled activation of the complement system and formation of the MAC can also contribute to tissue damage and inflammation in various diseases, such as autoimmune disorders, age-related macular degeneration, and ischemia-reperfusion injury.

Complement C1r is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Specifically, C1r is one of the three proteins that make up the C1 complex, which is the first component of the classical complement pathway.

The C1 complex is composed of C1q, C1r, and C1s, and it is activated by the binding of C1q to the Fc region of an antibody that is bound to a pathogen or damaged cell. Once activated, C1r undergoes a conformational change that allows it to cleave and activate C1s. Activated C1s then goes on to cleave and activate other components of the complement system, leading to the production of the membrane attack complex (MAC), which forms a pore in the membrane of the target cell and causes lysis.

Deficiencies or mutations in the genes encoding the proteins of the C1 complex can lead to immune disorders, including hereditary angioedema, which is characterized by recurrent episodes of swelling in various parts of the body.

Micropore filters are medical devices used to filter or sterilize fluids and gases. They are made of materials like cellulose, mixed cellulose ester, or polyvinylidene fluoride with precise pore sizes, typically ranging from 0.1 to 10 micrometers in diameter. These filters are used to remove bacteria, fungi, and other particles from solutions in laboratory and medical settings, such as during the preparation of injectable drugs, tissue culture media, or sterile fluids for medical procedures. They come in various forms, including syringe filters, vacuum filters, and bottle-top filters, and are often used with the assistance of a vacuum or positive pressure to force the fluid through the filter material.

Complement C7 is a protein that plays a role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Specifically, C7 is a component of the membrane attack complex (MAC), which is a group of proteins that forms a pore in the membrane of target cells, leading to their lysis or destruction.

C7 is activated when it binds to the C5b-7 complex, which is formed by the cleavage of C5 and C6 by the C5 convertase. Once bound to the C5b-7 complex, C7 undergoes a conformational change that allows it to insert into the target cell membrane. This forms the basis for the formation of the MAC and subsequent lysis of the target cell.

Deficiencies in complement components, including C7, can lead to increased susceptibility to certain infections and autoimmune disorders. Additionally, abnormal regulation of the complement system has been implicated in a variety of diseases, including inflammatory and degenerative conditions.

The "Classical Complement Pathway" is one of the three pathways that make up the complement system, which is a part of the immune system in humans and other animals. The complement system helps to enhance the ability of antibodies and phagocytic cells to clear pathogens from the body.

The Classical Complement Pathway is initiated by the binding of the first component of the complement system, C1, to an activator surface, such as an antigen-antibody complex. Activation of C1 results in the sequential activation of other components of the complement system, including C4 and C2, which form the C3 convertase (C4b2a). The C3 convertase cleaves the third component of the complement system, C3, into C3a and C3b. C3b then binds to the activator surface and forms a complex with other components of the complement system, leading to the formation of the membrane attack complex (MAC), which creates a pore in the membrane of the target cell, causing its lysis.

The Classical Complement Pathway plays an important role in the immune response to pathogens and can also contribute to inflammation and tissue damage in certain diseases, such as autoimmune disorders and allergies.

Blood proteins, also known as serum proteins, are a group of complex molecules present in the blood that are essential for various physiological functions. These proteins include albumin, globulins (alpha, beta, and gamma), and fibrinogen. They play crucial roles in maintaining oncotic pressure, transporting hormones, enzymes, vitamins, and minerals, providing immune defense, and contributing to blood clotting.

Albumin is the most abundant protein in the blood, accounting for about 60% of the total protein mass. It functions as a transporter of various substances, such as hormones, fatty acids, and drugs, and helps maintain oncotic pressure, which is essential for fluid balance between the blood vessels and surrounding tissues.

Globulins are divided into three main categories: alpha, beta, and gamma globulins. Alpha and beta globulins consist of transport proteins like lipoproteins, hormone-binding proteins, and enzymes. Gamma globulins, also known as immunoglobulins or antibodies, are essential for the immune system's defense against pathogens.

Fibrinogen is a protein involved in blood clotting. When an injury occurs, fibrinogen is converted into fibrin, which forms a mesh to trap platelets and form a clot, preventing excessive bleeding.

Abnormal levels of these proteins can indicate various medical conditions, such as liver or kidney disease, malnutrition, infections, inflammation, or autoimmune disorders. Blood protein levels are typically measured through laboratory tests like serum protein electrophoresis (SPE) and immunoelectrophoresis (IEP).

Complement C8 is a protein component of the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. Specifically, C8 is a part of the membrane attack complex (MAC), which forms a pore in the membrane of target cells, leading to their lysis or destruction.

C8 is composed of three subunits: alpha, beta, and gamma. It is activated when it binds to the complement component C5b67 complex on the surface of a target cell. Once activated, C8 undergoes a conformational change that allows it to insert into the target cell membrane and form a pore, which disrupts the cell's membrane integrity and can lead to its death.

Deficiencies in complement components, including C8, can make individuals more susceptible to certain infections and autoimmune diseases. Additionally, mutations in the genes encoding complement proteins have been associated with various inherited disorders, such as atypical hemolytic uremic syndrome (aHUS), which is characterized by thrombotic microangiopathy and kidney failure.

Complement C1 is a protein complex that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. The complement system consists of a group of proteins that work together to destroy microbes and remove debris.

Complement C1 is composed of three subunits: C1q, C1r, and C1s. When activated, C1q binds to the surface of a pathogen or damaged cell, leading to the activation of C1r and C1s. Activated C1r then cleaves and activates C1s, which in turn cleaves and activates other complement components, ultimately resulting in the formation of the membrane attack complex (MAC), a protein structure that forms a pore in the membrane of the target cell, leading to its lysis and destruction.

Defects in the complement component C1 can lead to immune disorders, such as hereditary angioedema, which is characterized by recurrent episodes of swelling in various parts of the body.

Complement Factor H is a protein involved in the regulation of the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Specifically, Complement Factor H helps to regulate the activation and deactivation of the complement component C3b, preventing excessive or unwanted activation of the complement system and protecting host tissues from damage.

Complement Factor H is a crucial protein in maintaining the balance between the protective effects of the complement system and the potential for harm to the body's own cells and tissues. Deficiencies or mutations in Complement Factor H have been associated with several diseases, including age-related macular degeneration (AMD), atypical hemolytic uremic syndrome (aHUS), and C3 glomerulopathy.

Anaphylatoxins are a group of small protein molecules that are released during an immune response, specifically as a result of the activation of the complement system. The term "anaphylatoxin" comes from their ability to induce anaphylaxis, a severe and rapid allergic reaction. There are three main anaphylatoxins, known as C3a, C4a, and C5a, which are derived from the cleavage of complement components C3, C4, and C5, respectively.

Anaphylatoxins play a crucial role in the immune response by attracting and activating various immune cells, such as neutrophils, eosinophils, and mast cells, to the site of infection or injury. They also increase vascular permeability, causing fluid to leak out of blood vessels and leading to tissue swelling. Additionally, anaphylatoxins can induce smooth muscle contraction, which can result in bronchoconstriction and hypotension.

While anaphylatoxins are important for the immune response, they can also contribute to the pathogenesis of various inflammatory diseases, such as asthma, arthritis, and sepsis. Therefore, therapies that target the complement system and anaphylatoxin production have been developed and are being investigated as potential treatments for these conditions.

Complement receptor 3b (CR3b or CD11b/CD18) is not a medical definition itself, but I can provide you with the relevant information regarding this term.

Complement receptor 3 (CR3) is a heterodimeric receptor consisting of two subunits, CD11b (also known as Mac-1 or CR3 alpha) and CD18 (also known as beta2 integrin). There are two forms of the CD11b/CD18 heterodimer: CR3a (CD11b/CD18) and CR3b (CD11b/CD18'). The difference between these two forms lies in the conformation of the CD11b subunit.

Complement receptor 3b (CR3b or CD11b/CD18') is a less common form of the CR3 receptor, which is primarily expressed on myeloid cells such as monocytes, macrophages, and neutrophils. CR3b has a higher affinity for complement component C3b and its fragments iC3b and C3dg compared to CR3a.

CR3b plays a role in various immune functions, including:

1. Phagocytosis: Binding of C3b or its fragments to CR3b facilitates the recognition and uptake of opsonized pathogens by phagocytes.
2. Adhesion: The integrin component of CR3b mediates cell-cell and cell-matrix interactions, contributing to leukocyte migration and recruitment to sites of inflammation or infection.
3. Intracellular signaling: Activation of CR3b can lead to intracellular signaling events that modulate immune responses, such as the release of pro-inflammatory cytokines and reactive oxygen species.

In summary, Complement receptor 3b (CR3b or CD11b/CD18') is a less common form of CR3 primarily expressed on myeloid cells that binds complement component C3b and its fragments with high affinity, mediating phagocytosis, adhesion, and intracellular signaling.

Complement C5b is a protein complex that forms during the activation of the complement system, which is a part of the immune system. The complement system helps to eliminate pathogens and damaged cells from the body by marking them for destruction and attracting immune cells to the site of infection or injury.

The complement component C5 is cleaved into two fragments, C5a and C5b, during the activation of the complement system. C5a is a small peptide that acts as a chemoattractant, drawing immune cells to the site of inflammation. C5b, on the other hand, forms a complex with other complement components (C6, C7, C8, and C9) to create the membrane attack complex (MAC). The MAC inserts itself into the membrane of the target cell, forming a pore that disrupts the cell's integrity and leads to its lysis or destruction.

Therefore, Complement C5b is an important protein involved in the immune response, specifically in the terminal phase of complement activation, which results in the formation of the MAC and subsequent destruction of target cells.

Complement C2a is a proteolytic fragment generated through the activation of the complement component C2 during the classical complement pathway. It is a serine protease that plays a crucial role in the formation of the C3 convertase (C4b2a) complex, which cleaves and activates the complement component C3 into C3a and C3b. This activation step is essential for the initiation of the immune response and elimination of pathogens through various effector mechanisms such as opsonization, phagocytosis, and formation of the membrane attack complex (MAC). Dysregulation or deficiency in complement components, including C2a, can lead to immunological disorders and increased susceptibility to infections.

The term "Receptor, Anaphylatoxin C5a" refers to a specific type of receptor found on the surface of various cells in the human body, including immune cells and endothelial cells. This receptor binds to a molecule called C5a, which is a cleavage product of the complement component C5 and is one of the most potent anaphylatoxins.

Anaphylatoxins are inflammatory mediators that play a crucial role in the immune response, particularly in the activation of the complement system and the recruitment of immune cells to sites of infection or injury. C5a is generated during the activation of the complement system and has a wide range of biological activities, including chemotaxis (attracting immune cells to the site of inflammation), increased vascular permeability, and the activation of immune cells such as neutrophils, monocytes, and mast cells.

The C5a receptor, also known as CD88, is a G protein-coupled receptor that belongs to the superfamily of seven transmembrane domain receptors. When C5a binds to the receptor, it triggers a series of intracellular signaling events that lead to the activation of various cellular responses, such as the release of inflammatory mediators and the recruitment of immune cells to the site of inflammation.

Abnormal activation of the C5a/C5a receptor pathway has been implicated in a variety of inflammatory diseases, including sepsis, acute respiratory distress syndrome (ARDS), and autoimmune disorders. Therefore, targeting this pathway with therapeutic agents has emerged as a promising strategy for the treatment of these conditions.

Erythrocytes, also known as red blood cells (RBCs), are the most common type of blood cell in circulating blood in mammals. They are responsible for transporting oxygen from the lungs to the body's tissues and carbon dioxide from the tissues to the lungs.

Erythrocytes are formed in the bone marrow and have a biconcave shape, which allows them to fold and bend easily as they pass through narrow blood vessels. They do not have a nucleus or mitochondria, which makes them more flexible but also limits their ability to reproduce or repair themselves.

In humans, erythrocytes are typically disc-shaped and measure about 7 micrometers in diameter. They contain the protein hemoglobin, which binds to oxygen and gives blood its red color. The lifespan of an erythrocyte is approximately 120 days, after which it is broken down in the liver and spleen.

Abnormalities in erythrocyte count or function can lead to various medical conditions, such as anemia, polycythemia, and sickle cell disease.

Complement inactivating agents are substances or drugs that inhibit the complement system, which is a part of the immune system responsible for the recognition and elimination of foreign substances and microorganisms. The complement system consists of a group of proteins that work together to help eliminate pathogens from the body.

Complement inactivating agents are used in medical settings to prevent or treat various conditions associated with excessive or unwanted activation of the complement system, such as inflammation, autoimmune diseases, and transplant rejection. These agents can inhibit different components of the complement pathway, including C1 esterase inhibitors, C3 convertase inhibitors, and C5a receptor antagonists.

Examples of complement inactivating agents include eculizumab, ravulizumab, and Alexion's Ultomiris, which are monoclonal antibodies that target C5, a protein involved in the final steps of the complement pathway. These drugs have been approved for the treatment of paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and other complement-mediated diseases.

Other complement inactivating agents include C1 esterase inhibitors, such as Berinert and Ruconest, which are used to treat hereditary angioedema (HAE). These drugs work by inhibiting the activation of the classical pathway of the complement system, thereby preventing the release of inflammatory mediators that can cause swelling and pain.

Overall, complement inactivating agents play an important role in the treatment of various complement-mediated diseases, helping to reduce inflammation, prevent tissue damage, and improve patient outcomes.

A Complement Hemolytic Activity Assay is a laboratory test used to measure the functionality and activity level of the complement system, which is a part of the immune system. The complement system is a group of proteins that work together to help eliminate pathogens from the body.

The assay measures the ability of the complement system to lyse (break open) red blood cells. This is done by mixing the patient's serum (the liquid portion of the blood) with antibody-coated red blood cells and incubating them together. The complement proteins in the serum will then bind to the antibodies on the red blood cells and cause them to lyse.

The degree of hemolysis (red blood cell lysis) is directly proportional to the activity level of the complement system. By measuring the amount of hemolysis, the assay can determine whether the complement system is functioning properly and at what level of activity.

This test is often used to diagnose or monitor complement-mediated diseases such as autoimmune disorders, infections, and some types of cancer. It may also be used to evaluate the effectiveness of treatments that target the complement system.

Complement receptor 3d (CR3d or CD11b/CD18) is not a medical definition in itself, but rather a specific type of integrin receptor that plays a crucial role in the immune system. Here's a breakdown of the components:

1. Complement Receptors: These are proteins found on the surface of various cells, including white blood cells (leukocytes), that recognize and bind to complement components, which are proteins involved in the immune response. The binding of complement components to their receptors helps facilitate communication between cells, enhances phagocytosis (the process by which certain cells engulf and destroy foreign particles or microorganisms), and contributes to the inflammatory response.
2. CR3 (Complement Receptor 3): Complement Receptor 3 is a heterodimeric receptor composed of two subunits, CD11b (also known as integrin alpha M) and CD18 (also known as integrin beta 2). Together, they form the integrin Mac-1 or αMβ2.
3. CR3d (CD11b/CD18): CR3d specifically refers to the CD11b subunit of the Complement Receptor 3 heterodimer. The CD11b subunit is responsible for recognizing and binding to complement component C3b, iC3b, and C4b fragments, as well as other ligands such as fibrinogen, ICAM-1 (Intercellular Adhesion Molecule 1), and factor X.

In summary, Complement Receptor 3d (CR3d or CD11b/CD18) is a type of integrin receptor found on the surface of various immune cells that recognizes and binds to complement components C3b, iC3b, and C4b fragments, as well as other ligands. This binding facilitates communication between cells, enhances phagocytosis, and contributes to the inflammatory response.

Complement fixation tests are a type of laboratory test used in immunology and serology to detect the presence of antibodies in a patient's serum. These tests are based on the principle of complement activation, which is a part of the immune response. The complement system consists of a group of proteins that work together to help eliminate pathogens from the body.

In a complement fixation test, the patient's serum is mixed with a known antigen and complement proteins. If the patient has antibodies against the antigen, they will bind to it and activate the complement system. This results in the consumption or "fixation" of the complement proteins, which are no longer available to participate in a secondary reaction.

A second step involves adding a fresh source of complement proteins and a dye-labeled antibody that recognizes a specific component of the complement system. If complement was fixed during the first step, it will not be available for this secondary reaction, and the dye-labeled antibody will remain unbound. Conversely, if no antibodies were present in the patient's serum, the complement proteins would still be available for the second reaction, leading to the binding of the dye-labeled antibody.

The mixture is then examined under a microscope or using a spectrophotometer to determine whether the dye-labeled antibody has bound. If it has not, this indicates that the patient's serum contains antibodies specific to the antigen used in the test, and a positive result is recorded.

Complement fixation tests have been widely used for the diagnosis of various infectious diseases, such as syphilis, measles, and influenza. However, they have largely been replaced by more modern serological techniques, like enzyme-linked immunosorbent assays (ELISAs) and nucleic acid amplification tests (NAATs), due to their increased sensitivity, specificity, and ease of use.

Complement Factor D is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Specifically, Factor D is a serine protease that is involved in the alternative pathway of the complement system.

In this pathway, Factor D helps to cleave another protein called Factor B, which then activates a complex called the C3 convertase. The C3 convertase cleaves complement component 3 (C3) into C3a and C3b, leading to the formation of the membrane attack complex (MAC), which creates a pore in the membrane of the target cell, causing its lysis and removal from the body.

Deficiencies or mutations in Complement Factor D can lead to an impaired alternative pathway and increased susceptibility to certain infections, particularly those caused by Neisseria bacteria. Additionally, abnormal regulation of the complement system has been implicated in a variety of diseases, including autoimmune disorders, inflammatory conditions, and neurodegenerative diseases.

An antigen-antibody complex is a type of immune complex that forms when an antibody binds to a specific antigen. An antigen is any substance that triggers an immune response, while an antibody is a protein produced by the immune system to neutralize or destroy foreign substances like antigens.

When an antibody binds to an antigen, it forms a complex that can be either soluble or insoluble. Soluble complexes are formed when the antigen is small and can move freely through the bloodstream. Insoluble complexes, on the other hand, are formed when the antigen is too large to move freely, such as when it is part of a bacterium or virus.

The formation of antigen-antibody complexes plays an important role in the immune response. Once formed, these complexes can be recognized and cleared by other components of the immune system, such as phagocytes, which help to prevent further damage to the body. However, in some cases, the formation of large numbers of antigen-antibody complexes can lead to inflammation and tissue damage, contributing to the development of certain autoimmune diseases.

Complement Factor I is a protein involved in the regulation of the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. Specifically, Complement Factor I is a serine protease that regulates the complement component C3b by cleaving it into inactive fragments, thereby preventing the excessive activation of the complement system and protecting host tissues from damage.

Complement Factor I functions in conjunction with other regulatory proteins, such as complement receptor 1 (CR1) and membrane cofactor protein (MCP), to control the activity of the complement system at various stages. Deficiencies or mutations in Complement Factor I have been associated with several diseases, including atypical hemolytic uremic syndrome (aHUS), age-related macular degeneration (AMD), and systemic lupus erythematosus (SLE).

Complement C4b-binding protein (C4bp) is a regulatory protein in the complement system, which is a part of the immune system that helps to clear pathogens and damaged cells from the body. C4bp regulates the complement system by binding to and inhibiting the activity of C4b, an activated component of the classical and lectin pathways of the complement system. By doing so, C4bp helps to prevent excessive or inappropriate activation of the complement system, which could otherwise lead to tissue damage and inflammation.

C4bp is a complex protein that consists of several subunits, including a central α-chain and multiple β-chains. It is produced by liver cells and can also be found on the surface of some cells in the body. Mutations in the genes encoding C4bp have been associated with certain immune disorders, such as systemic lupus erythematosus (SLE) and atypical hemolytic uremic syndrome (aHUS).

CD55, also known as Decay-accelerating factor (DAF), is a protein that acts as an inhibitor of the complement system, which is a part of the immune system. It prevents the formation of the membrane attack complex (MAC) on host cells and tissues, thereby protecting them from damage caused by the complement activation. CD55 is found on the surface of many types of cells in the body, including red blood cells, white blood cells, and cells lining the blood vessels.

As an antigen, CD55 is a molecule that can be recognized by the immune system and stimulate an immune response. However, unlike some other antigens, CD55 does not typically elicit a strong immune response because it is a self-antigen, meaning it is normally present in the body and should not be targeted by the immune system.

In certain medical conditions, such as autoimmune disorders or transplant rejection, the immune system may mistakenly attack cells expressing CD55. In these cases, measuring the levels of CD55 antigens can provide valuable diagnostic information and help guide treatment decisions.

Complement C3-C5 convertases are protease complexes that play a crucial role in the classical pathway of the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body.

The complement system consists of a group of plasma proteins that work together to help eliminate foreign substances and initiate the inflammatory response. The classical pathway is initiated when an antibody binds to a pathogen or antigen, forming an antigen-antibody complex. This complex then activates the first protein in the classical pathway, C1, which subsequently activates the next protein, C4, and then C2.

The resulting complex of C4 and C2 (C4b2a) is called the C3 convertase of the classical pathway. This enzyme cleaves the complement component C3 into C3a and C3b. The C3b fragment then binds to the surface of the pathogen or antigen, forming a new complex with other complement components (C3bBb), which is called the C5 convertase of the classical pathway.

The C5 convertase cleaves the complement component C5 into C5a and C5b. The C5b fragment then initiates the formation of the membrane attack complex (MAC), which creates a pore in the membrane of the pathogen or cell, leading to its lysis and elimination.

Therefore, the Complement C3-C5 convertases, Classical Pathway are essential components of the classical pathway of the complement system that help to eliminate pathogens and damaged cells from the body by activating the complement system and initiating the membrane attack complex.

Complement C2b is a proteolytic fragment generated through the activation of the complement component C2, which is a part of the complement system. The complement system is a group of plasma proteins that play an important role in the body's immune defense against pathogens and abnormal cells.

When the complement component C2 is activated by the C3 convertase (a complex formed by C3b and either C4b or C4d), it is cleaved into two fragments: C2a and C2b. The C2b fragment is a smaller piece that contains an active protease domain, which can cleave other proteins in the complement pathway.

C2b plays a role in the formation of the membrane attack complex (MAC), a protein structure that forms pores in the membranes of target cells, leading to their lysis and removal by the immune system. Dysregulation or overactivation of the complement system, including C2b, can contribute to various pathological conditions such as autoimmune diseases, inflammatory disorders, and tissue damage.

CD59 is a type of protein found on the surface of many cells in the human body, including red and white blood cells, that functions as an inhibitor of the complement system. The complement system is a part of the immune system that helps to eliminate pathogens such as bacteria and viruses from the body.

CD59 specifically inhibits the formation of the membrane attack complex (MAC), which is a protein structure that forms pores in the cell membrane and can lead to cell lysis or death. By preventing the formation of the MAC, CD59 helps to protect cells from complement-mediated damage.

As an antigen, CD59 is a molecule that can be recognized by the immune system and stimulate an immune response. However, because it is a self-protein found on normal human cells, CD59 is not typically targeted by the immune system unless there is some kind of dysregulation or abnormality.

In certain medical conditions, such as autoimmune disorders or transplant rejection, the immune system may mistakenly target CD59 or other self-proteins, leading to damage to healthy cells and tissues. In these cases, treatments may be necessary to modulate or suppress the immune response and prevent further harm.

Lysine carboxypeptidase is not a widely recognized or used medical term. However, in biochemistry, carboxypeptidases are enzymes that cleave peptide bonds at the carboxyl-terminal end of a protein or peptide. If there is a specific enzyme named "lysine carboxypeptidase," it would be an enzyme that selectively removes lysine residues from the carboxyl terminus of a protein or peptide.

There are several enzymes that can act as carboxypeptidases, and some of them have specificities for certain amino acids, such as arginine or lysine. These enzymes play important roles in various biological processes, including protein degradation, processing, and regulation.

It's worth noting that the term "lysine carboxypeptidase" may refer to different enzymes depending on the context, such as bacterial or mammalian enzymes, and they may have different properties and functions.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Immunoelectrophoresis (IEP) is a laboratory technique used in the field of clinical pathology and immunology. It is a method for separating and identifying proteins, particularly immunoglobulins or antibodies, in a sample. This technique combines the principles of electrophoresis, which separates proteins based on their electric charge and size, with immunological reactions, which detect specific proteins using antigen-antibody interactions.

In IEP, a protein sample is first separated by electrophoresis in an agarose or agar gel matrix on a glass slide or in a test tube. After separation, an antibody specific to the protein of interest is layered on top of the gel and allowed to diffuse towards the separated proteins. This creates a reaction between the antigen (protein) and the antibody, forming a visible precipitate at the point where they meet. The precipitate line's position and intensity can then be analyzed to identify and quantify the protein of interest.

Immunoelectrophoresis is particularly useful in diagnosing various medical conditions, such as immunodeficiency disorders, monoclonal gammopathies (like multiple myeloma), and other plasma cell dyscrasias. It can help detect abnormal protein patterns, quantify specific immunoglobulins, and identify the presence of M-proteins or Bence Jones proteins, which are indicative of monoclonal gammopathies.

Cytochrome P-450 CYP2B1 is a specific isoform of the cytochrome P-450 enzyme system, which is involved in the metabolism of drugs and other xenobiotics in the liver. This particular isoenzyme is primarily found in rats and is responsible for the metabolism of a variety of substrates, including certain drugs, steroids, and environmental toxins.

The cytochrome P-450 system is a group of enzymes located in the endoplasmic reticulum of cells, particularly in the liver. These enzymes play a crucial role in the metabolism of various substances, including drugs, hormones, and toxins. They work by catalyzing oxidation-reduction reactions that convert lipophilic compounds into more hydrophilic ones, which can then be excreted from the body.

CYP2B1 is one of many isoforms of cytochrome P-450, and it has a preference for certain types of substrates. It is involved in the metabolism of drugs such as cyclophosphamide, ifosfamide, and methadone, as well as steroids like progesterone and environmental toxins like pentachlorophenol.

It's important to note that while CYP2B1 is an essential enzyme in rats, its human counterpart, CYP2B6, plays a similar role in drug metabolism in humans. Understanding the function and regulation of these enzymes can help in predicting drug interactions, designing new drugs, and tailoring therapies to individual patients based on their genetic makeup.

Phagocytosis is the process by which certain cells in the body, known as phagocytes, engulf and destroy foreign particles, bacteria, or dead cells. This mechanism plays a crucial role in the immune system's response to infection and inflammation. Phagocytes, such as neutrophils, monocytes, and macrophages, have receptors on their surface that recognize and bind to specific molecules (known as antigens) on the target particles or microorganisms.

Once attached, the phagocyte extends pseudopodia (cell extensions) around the particle, forming a vesicle called a phagosome that completely encloses it. The phagosome then fuses with a lysosome, an intracellular organelle containing digestive enzymes and other chemicals. This fusion results in the formation of a phagolysosome, where the engulfed particle is broken down by the action of these enzymes, neutralizing its harmful effects and allowing for the removal of cellular debris or pathogens.

Phagocytosis not only serves as a crucial defense mechanism against infections but also contributes to tissue homeostasis by removing dead cells and debris.

Cobra venoms are a type of snake venom that is produced by cobras, which are members of the genus Naja in the family Elapidae. These venoms are complex mixtures of proteins and other molecules that have evolved to help the snake immobilize and digest its prey.

Cobra venoms typically contain a variety of toxic components, including neurotoxins, hemotoxins, and cytotoxins. Neurotoxins target the nervous system and can cause paralysis and respiratory failure. Hemotoxins damage blood vessels and tissues, leading to internal bleeding and organ damage. Cytotoxins destroy cells and can cause tissue necrosis.

The specific composition of cobra venoms can vary widely between different species of cobras, as well as between individual snakes of the same species. Some cobras have venoms that are primarily neurotoxic, while others have venoms that are more hemotoxic or cytotoxic. The potency and effects of cobra venoms can also be influenced by factors such as the age and size of the snake, as well as the temperature and pH of the environment.

Cobra bites can be extremely dangerous and even fatal to humans, depending on the species of cobra, the amount of venom injected, and the location of the bite. Immediate medical attention is required in the event of a cobra bite, including the administration of antivenom therapy to neutralize the effects of the venom.

Steroid 21-hydroxylase, also known as CYP21A2, is a crucial enzyme involved in the synthesis of steroid hormones in the adrenal gland. Specifically, it catalyzes the conversion of 17-hydroxyprogesterone to 11-deoxycortisol and progesterone to deoxycorticosterone in the glucocorticoid and mineralocorticoid pathways, respectively.

Deficiency or mutations in this enzyme can lead to a group of genetic disorders called congenital adrenal hyperplasia (CAH), which is characterized by impaired cortisol production and disrupted hormonal balance. Depending on the severity of the deficiency, CAH can result in various symptoms such as ambiguous genitalia, precocious puberty, sexual infantilism, infertility, and increased risk of adrenal crisis.

Chloromercurinitrophenols are organic compounds that contain a mercury atom, a chlorine atom, a nitro group (-NO2), and a phenol group (-C6H5OH). They have the general formula C6H4ClHgNO2. These compounds were once used in medicine as antiseptics and preservatives, but their use has been largely discontinued due to their toxicity and environmental persistence.

The complement system is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. The alternative pathway is one of three pathways that can activate the complement system. Complement C3-C5 convertases are proteins that play a crucial role in the activation of the complement system through the alternative pathway.

Complement C3-C5 convertases are formed by the cleavage of complement component C3 into C3a and C3b by the C3 convertase enzyme. The C3b fragment then binds to the surface of a pathogen or damaged cell, forming a new complex called the C3bBb convertase. This complex can then cleave additional C3 molecules into C3a and C3b fragments, leading to the amplification of the complement response.

The C3bBb convertase can also cleave complement component C5 into C5a and C5b fragments. The C5b fragment then forms a complex with other complement components to form the membrane attack complex (MAC), which creates a pore in the membrane of the pathogen or damaged cell, leading to its lysis and elimination from the body.

Therefore, Complement C3-C5 convertases, Alternative Pathway refer to the enzyme complexes that play a critical role in the activation of the complement system through the alternative pathway, ultimately leading to the destruction of pathogens or damaged cells.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Angioedema is a medical condition characterized by rapid swelling of the skin, mucous membranes, and submucosal tissues. The swelling typically occurs in the face, lips, tongue, larynx, and extremities, and can also affect the gastrointestinal tract. Angioedema can be caused by a variety of factors, including allergic reactions, hereditary genetic mutations, and certain medications.

In medical terms, angioedema is defined as a self-limiting episode of localized edema in the deep dermis, subcutaneous tissue, or mucous membranes, characterized by well-circumscribed, nonpitting, nondependent swelling. The swelling can occur suddenly and may persist for up to 72 hours. In severe cases, angioedema can cause airway obstruction and be life-threatening if not treated promptly.

Angioedema can be classified into two main types: allergic or non-allergic. Allergic angioedema is caused by an immune response to an allergen, such as food, medication, or insect venom. Non-allergic angioedema can be further divided into several subtypes, including hereditary angioedema (HA), acquired angioedema (AAE), and drug-induced angioedema.

Hereditary angioedema is a rare genetic disorder caused by mutations in the C1 inhibitor gene, leading to uncontrolled activation of the complement system and increased production of bradykinin, a potent vasodilator. Acquired angioedema is similar to hereditary angioedema but occurs later in life and is associated with underlying medical conditions such as lymphoproliferative disorders or autoimmune diseases. Drug-induced angioedema can be caused by a variety of medications, including ACE inhibitors, angiotensin receptor blockers (ARBs), and nonsteroidal anti-inflammatory drugs (NSAIDs).

The diagnosis of angioedema is typically based on clinical presentation, medical history, and laboratory tests. Treatment depends on the underlying cause of the condition but may include antihistamines, corticosteroids, epinephrine, and medications that target the complement system or bradykinin pathway. In severe cases, hospitalization and intensive care may be necessary to manage airway obstruction and other complications.

The Complement C1 Inhibitor protein, also known as C1-INH, is a protein involved in the regulation of the complement system and the contact system, which are parts of the immune system. The complement system helps to eliminate pathogens (e.g., bacteria, viruses) from the body, while the contact system helps to regulate blood coagulation and inflammation.

C1-INH works by inhibiting the activation of C1, an enzyme complex that is the first component of the classical complement pathway. By inhibiting C1, C1-INH prevents the activation of downstream components of the complement system, thereby helping to regulate the immune response and prevent excessive inflammation.

Deficiencies or dysfunction in the C1-INH protein can lead to a group of genetic disorders known as C1 inhibitor deficiency disorders, which include hereditary angioedema (HAE) and acquired angioedema (AAE). These conditions are characterized by recurrent episodes of swelling in various parts of the body, such as the face, hands, feet, and airway, which can be painful and potentially life-threatening if they affect the airway.

... , also known as C3b/C4b inactivator, is a protein that in humans is encoded by the CFI gene. Complement ... either C3b or C4b) and a cofactor protein (Factor H, C4b-binding protein, complement receptor 1, and membrane cofactor protein ... Whaley K (March 1980). "Biosynthesis of the complement components and the regulatory proteins of the alternative complement ... is a protein of the complement system, first isolated in 1966 in guinea pig serum, that regulates complement activation by ...
Factor I requires a C3b-binding protein cofactor such as complement factor H, CR1, or Membrane Cofactor of Proteolysis (MCP or ... Pangburn MK, Schreiber RD, Müller-Eberhard HJ (July 1977). "Human complement C3b inactivator: isolation, characterization, and ... cells from complement-mediated damage. CFHR5 (Complement Factor H-Related protein 5) is able to bind to act as a cofactor for ... Since C3b is free and abundant in the plasma, it can bind to either a host cell or a pathogen surface. To prevent complement ...
C4b-binding protein inhibits the haemolytic function of cell-bound C4b. C4b-binding protein and C3b inactivator control the C3 ... complement receptor 1 (CR1), C4b-binding protein and Factor H. Convertase assembly is suppressed by the proteolytic cleavage of ... "Modulation of the Classical Pathway C3 Convertase by Plasma Proteins C4 Binding Protein and C3b Inactivator". Proc Natl Acad ... in addition to enhancing proteolytic inactivation of C3b by C3b inactivator (C3bINA - endopeptidase). Membrane-associated ...
... complement c3b inactivator proteins MeSH D12.776.124.486.274.920.325.200 - complement factor h MeSH D12.776.124.486.274.920. ... complement c1 inactivator proteins MeSH D12.776.124.486.274.920.250.500 - complement c1 inhibitor protein MeSH D12.776.124.486. ... complement factor b MeSH D12.776.124.486.274.920 - complement inactivator proteins MeSH D12.776.124.486.274.920.124 - antigens ... complement c3 MeSH D12.776.124.486.274.250.250 - complement c3a MeSH D12.776.124.486.274.250.260 - complement c3b MeSH D12.776. ...
Complement C3b/C4b Receptor 1, CR1 (CD35) Complement Regulator of the Immunoglobulin Superfamily, CRIg Soluble complement ... Complement+Inactivator+Proteins at the U.S. National Library of Medicine Medical Subject Headings (MeSH) (CS1: long volume ... Complement control protein are proteins that interact with components of the complement system. The complement system is ... Complement control proteins also play a role in malignancy. Complement proteins protect against malignant cells- both by direct ...
Complement factor I, also known as C3b/C4b inactivator, is a protein that in humans is encoded by the CFI gene. Complement ... either C3b or C4b) and a cofactor protein (Factor H, C4b-binding protein, complement receptor 1, and membrane cofactor protein ... Whaley K (March 1980). "Biosynthesis of the complement components and the regulatory proteins of the alternative complement ... is a protein of the complement system, first isolated in 1966 in guinea pig serum, that regulates complement activation by ...
Next-day shipping cDNA ORF clones derived from Cfi complement factor I available at GenScript, starting from $99.00. ... General protein information. Preferred Names. complement factor I. Names. complement factor I. C3B/C4B inactivator ... mouse homolog is a regulatory serine proteinase of the complement cascade that cleaves C3b and C4b and inactivates them [RGD, ... Protein expression is influenced by many factors that may vary between experiments or laboratories. In addition, please pay ...
... is a serine protease that inactivates C3b and C4b in the presence of a co-factor protein, such as complement factor H (FH) and ... and classical pathways of complement activation by binding to C3b or C4b and acting as a co-factor to the inactivator enzyme ... Mutations in complement regulatory proteins predispose to preeclampsia: a genetic analysis of the PROMISSE cohort. PLoS Med. ( ... Complement system is an ancient part of innate immunity, which consists of cell surface-bound and freely circulating proteins ...
Learn about the three pathways lead to complement activation and some of their key inhibitors. ... Complement inhibitors include the plasma serine proteinase inhibitor serpin (C1 inactivator). The plasma proteins, Factor I and ... Note, C3b generated in the classical pathway feeds into the alternative pathway to amplify the activation of complement. ... Most of the C3b generated by the convertase is hydrolysed. However, if C3b comes into contact with an invading micro-organism ...
Complement C3b Inactivator Proteins 47% * Therapeutic Uses 27% * Complement C4b 20% 3 Citations (Scopus) ... Effects of Protein Supplementation Combined with Resistance Exercise Training on Walking Speed Recovery in Older Adults with ... Targeting therapeutic agent against C3b/C4b, SB002, on the inflammation-induced bone loss in experimental periodontitis. Huang ... Correlation between C-reactive protein and postoperative mortality in patients undergoing hip fracture surgery: a meta-analysis ...
The CFI gene provides instructions for making a protein called complement factor I. Learn about this gene and related health ... C3B/C4B inactivator. *C3BINA. *CFAI_HUMAN. *complement component I. *complement control protein factor I ... The CFI gene provides instructions for making a protein called complement factor I. This protein helps regulate a part of the ... Complement factor I and several related proteins protect healthy cells by preventing activation of the complement system when ...
Protein function: C4BP controls the classical pathway of complement activation. It binds as a cofactor to C3b/C4b inactivator ( ... It also accelerates the degradation of the C4bc2a complex (C3 convertase) by dissociating the complement fragment C2a. Alpha ... It interacts also with anticoagulant protein S and with serum amyloid P component. ... C3bina), which then hydrolyzes the complement fragment C4b. ... C4b-binding protein alpha chain precursor. *Proline-rich ...
Complement receptor 1 (CR1) has factor H-like activity, permitting factor I to cleave C3b. Membrane cofactor protein also has ... Table 3. Proteins of the Human Complement (C) System, Lectin Pathway *Table 4. Proteins of the Human Complement (C) System, C3 ... Table 1. Proteins of the Human Complement (C) System, Classical Pathway* *Table 2. Proteins of the Human Complement (C) System ... Table 6. Proteins of the Human Complement (C) System, Membrane Receptor and Control Proteins (Open Table in a new window) ...
This binding is dependent on the expression of proteins termed complement-regulator acquiring surface proteins (CRASPs). The ... Serum-resistant B. burgdorferi strains bind complement factor H (FH) and FH-like protein 1 (FHL-1) on the spirochaete surface. ... Our analysis indicates that its protein topology apparently evolved to provide a high affinity interaction site for FH/FHL-1 ... This work demonstrates that pathogens interact with complement regulators in ways that are distinct from the mechanisms used by ...
... attack by acquisition host complement regulators FHL-1 and factor H via complement regulator-acquiring surface proteins ( ... BbCRASPs). The BbCRASP-1 protein is the first bacterial factor H/FHL-1-binding protein for which the atomic structure has been ... Previously, 3 regions including the C terminus were identified as putative contact sites for the two complement regulators by ... of both complement regulators. Mapping the mutations onto the atomic structure of BbCRASP-1 reveals that, in contrast to ...
... inactivator) immunological test system.. 21:8.0.1.1.20.6.1.20. SECTION 866.5260. 866.5260 Complement C3b inactivator ... 866.5270 C-reactive protein immunological test system.. 21:8.0.1.1.20.6.1.22. SECTION 866.5320. 866.5320 Properdin factor B ... 866.5240 Complement components immunological test system.. 21:8.0.1.1.20.6.1.19. SECTION 866.5250. 866.5250 Complement C1 ... 866.5150 Bence-Jones proteins immunological test system.. 21:8.0.1.1.20.6.1.11. SECTION 866.5160. 866.5160 Beta-globulin ...
Complement C1 Inactivator Proteins. *Complement C3 Nephritic Factor. *Complement C3b Inactivator Proteins ... "Complement Inactivator Proteins" by people in UAMS Profiles by year, and whether "Complement Inactivator Proteins" was a major ... Complement Inactivator Proteins*Complement Inactivator Proteins. *Inactivator Proteins, Complement. *Proteins, Complement ... "Complement Inactivator Proteins" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH ( ...
Complement C3b Inactivator Proteins. * Complement C3b Inactivator Proteins. * Complement Factor H. * Complement Factor H ... The OspE-related proteins inhibit complement deposition and enhance serum resistance of Borrelia burgdorferi, the lyme disease ... The OspE-related proteins inhibit complement deposition and enhance serum resistance of Borrelia burgdorferi, the lyme disease ... The OspE-related proteins inhibit complement deposition and enhance serum resistance of Borrelia burgdorferi, the lyme disease ...
Factors, Conglutinogen Activating use Complement C3b Inactivator Proteins Factors, Cord use Cord Factors ... FADD Protein, Fas Associating use Fas-Associated Death Domain Protein FADD Protein, Fas-Associating use Fas-Associated Death ... FADD, Fas-Associating Protein use Fas-Associated Death Domain Protein Fade, Neuromuscular use Refractory Period, ... F Box and WD 40 Domain Containing Protein 7 use F-Box-WD Repeat-Containing Protein 7 ...
Factors, Conglutinogen Activating use Complement C3b Inactivator Proteins Factors, Cord use Cord Factors ... FADD Protein, Fas Associating use Fas-Associated Death Domain Protein FADD Protein, Fas-Associating use Fas-Associated Death ... FADD, Fas-Associating Protein use Fas-Associated Death Domain Protein Fade, Neuromuscular use Refractory Period, ... F Box and WD 40 Domain Containing Protein 7 use F-Box-WD Repeat-Containing Protein 7 ...
Factors, Conglutinogen Activating use Complement C3b Inactivator Proteins Factors, Cord use Cord Factors ... FADD Protein, Fas Associating use Fas-Associated Death Domain Protein FADD Protein, Fas-Associating use Fas-Associated Death ... FADD, Fas-Associating Protein use Fas-Associated Death Domain Protein Fade, Neuromuscular use Refractory Period, ... F Box and WD 40 Domain Containing Protein 7 use F-Box-WD Repeat-Containing Protein 7 ...
Factors, Conglutinogen Activating use Complement C3b Inactivator Proteins Factors, Cord use Cord Factors ... FADD Protein, Fas Associating use Fas-Associated Death Domain Protein FADD Protein, Fas-Associating use Fas-Associated Death ... FADD, Fas-Associating Protein use Fas-Associated Death Domain Protein Fade, Neuromuscular use Refractory Period, ... Factor-1, Myeloid Cell use Myeloid Cell Leukemia Sequence 1 Protein Factor-4A1, Eukaryotic Initiation use Eukaryotic Initiation ...
Factors, Conglutinogen Activating use Complement C3b Inactivator Proteins Factors, Cord use Cord Factors ... FADD Protein, Fas Associating use Fas-Associated Death Domain Protein FADD Protein, Fas-Associating use Fas-Associated Death ... FADD, Fas-Associating Protein use Fas-Associated Death Domain Protein Fade, Neuromuscular use Refractory Period, ... F Box and WD 40 Domain Containing Protein 7 use F-Box-WD Repeat-Containing Protein 7 ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
Complement 3a. Complement C3a. Complement 3b. Complement C3b. Complement 3b Inactivators. Complement C3b Inactivator Proteins. ... Complement Inactivators. Complement Inactivator Proteins. DNA-Binding Protein, Cyclic AMP-Responsive. Cyclic AMP Response ... Proto-Oncogene Protein c-met. Proto-Oncogene Proteins c-met. Proto-Oncogene Protein p21(ras). Proto-Oncogene Proteins p21(ras) ... Complement. Complement System Proteins. Complement 1. Complement C1. Complement 1 Inactivators. Complement C1 Inactivator ...
... and use of this information for rational design or identification of complement-inhibiting drugs are disclosed. ... The structure of C3c in complex with the complement inhibitor, compstatin, ... Notably, in the crystal of C3b, a C3b-C3b binding site is formed by the same face of the MG-ring (see FIG. 4A. ) (Janssen et al ... Physicochemical and residue conservation calculations to improve the ranking of protein-protein docking solutions. Protein Sci ...
Complement C3b Inactivator Proteins [D12.776.124.486.274.920.325] Complement C3b Inactivator Proteins ... Inactivators, Serum Complement Proteins, Complement Inactivating Proteins, Complement Inactivator Serum Complement Inactivators ... Inactivating Proteins, Complement. Inactivator Proteins, Complement. Inactivators, Serum Complement. Proteins, Complement ... Complement Inactivating Proteins Complement Inactivators, Serum Inactivating Proteins, Complement Inactivator Proteins, ...
Complement receptor binding of C3b-coated cells treated with C3b inactivator, beta 1H globulin and trypsin. On rotary dial ... You start by eating 40 grams of net carbs, 4 to 6-ounce servings of protein and 2 to 4 servings of fat per day. There is no way ... The top line shows the log scale proximity of the signaling proteins to the transcription factors, from the closest on the left ... she took thirty drops three times a day complemented with an unspecified dose of vitamin C. Test values are used as a reference ...
Inhibition of complement activation via the overexpression of complement-regulatory proteins (CRPs), most notably CD46, CD55 ... Complement activation in the presence of NHS indicated mainly effective although incomplete protection against C3b/iC3b/C3c ... C3a-induced ATF6 expression and DAF loss was inhibited using pertussis toxin (an enzymatic inactivator of G-protein coupled ... The adhesion G protein-coupled receptor CD97 and its ligand complement decay-accelerating factor CD55 are important binding ...
Wyatt, R.J.; Forristal, J.; West, C.D. 1979: Complement c 4b complement c 3b inactivator cofactor an essential control protein ... Chenoweth, D.E. 1987: Complement activation by biomaterials immunodetection of surface bound c3b and fluid phase anaphylatoxins ... Complement c 3 nephritic factor protection of bound complement c 3 from breakdown by complement c 3b c 4b inactivator and the ... Complement c 3b inactivation isolation and structural analysis of complement c 3c complement c 3dg alpha 2d and complement c 3g ...
  • Complement factor I (factor I) is a protein of the complement system, first isolated in 1966 in guinea pig serum, that regulates complement activation by cleaving cell-bound or fluid phase C3b and C4b. (wikipedia.org)
  • It interacts also with anticoagulant protein S and with serum amyloid P component. (lu.se)
  • The complement system as understood today is a multimolecular system composed of more than 32 proteins and consisting of serum proteins, serosal proteins, and cell membrane receptors that bind to complement fragments. (medscape.com)
  • The complement system consists of 7 serum and 9 membrane regulatory proteins, 1 serosal regulatory protein, and 8 cell membrane receptors that bind complement fragments. (medscape.com)
  • Serum-resistant B. burgdorferi strains bind complement factor H (FH) and FH-like protein 1 (FHL-1) on the spirochaete surface. (ox.ac.uk)
  • Serum proteins that negatively regulate the cascade process of COMPLEMENT ACTIVATION. (uams.edu)
  • The OspE-related proteins inhibit complement deposition and enhance serum resistance of Borrelia burgdorferi, the lyme disease spirochete. (ouhsc.edu)
  • Complement-dependent cytotoxicity (CDC), which eliminates aberrant target cells through the assembly and complex formation of serum complement molecules, is one of the major effector functions of anticancer therapeutic antibodies. (bvsalud.org)
  • It binds as a cofactor to C3b/C4b inactivator (C3bina), which then hydrolyzes the complement fragment C4b. (lu.se)
  • Here, C3b binds to factor B that is cleaved by factor D to Bb. (medscape.com)
  • describes the use of a phage-displayed combinatorial random peptide library to identify a 27-residue peptide that binds to C3 and inhibits complement activation. (justia.com)
  • Proteolytic activation of C3 yields C3b, which covalently binds to pathogenic or self surfaces providing a strong signal for clearance of the tagged particles. (justia.com)
  • Structure-function mapping of BbCRASP-1, the key complement factor H and FHL-1 binding protein of Borrelia burgdorferi. (ox.ac.uk)
  • Mutational analyses of the BbCRASP-1 protein of Borrelia burgdorferi identify residues relevant for the architecture and binding of host complement regulators FHL-1 and factor H. (ox.ac.uk)
  • mouse homolog is a regulatory serine proteinase of the complement cascade that cleaves C3b and C4b and inactivates them [RGD, Feb 2006]. (genscript.com)
  • C2a in the convertase complex cleaves C3 releasing C3a and C3b. (abcam.com)
  • This then acts similarly to C1 esterase and cleaves C2 and C4 to form C2aC4b, which is the C3 esterase that cleaves C3 to form C3b. (medscape.com)
  • Many of the substances under investigation possess the disadvantage of being a large molecular weight proteins that are difficult to manufacture and must be administered by infusion. (justia.com)
  • This domain contains the catalytic triad His-362, Asp-411, and Ser-507, which is responsible for specific cleavage of C3b and C4b. (wikipedia.org)
  • Following these cleavage events, complement pathway activation continues as in the classical pathway. (abcam.com)
  • The second phase for each involves cleavage of C3b, generating multiple biologically important fragments and large, potentially cytolytic complexes. (medscape.com)
  • the classical pathway initiated by antibodies bound to the surface of foreign bodies and the alternative and lectin pathways that provide an antibody-independent mechanism for complement activation, induced by the presence of bacteria and other micro-organisms. (abcam.com)
  • C4BP controls the classical pathway of complement activation. (lu.se)
  • the heavy chain plays an inhibitory role in maintaining the enzyme inactive until it meets the complex formed by the substrate (either C3b or C4b) and a cofactor protein (Factor H, C4b-binding protein, complement receptor 1, and membrane cofactor protein). (wikipedia.org)
  • This binding is dependent on the expression of proteins termed complement-regulator acquiring surface proteins (CRASPs). (ox.ac.uk)
  • One central immune escape mechanism is the inactivation of the host complement attack by acquisition host complement regulators FHL-1 and factor H via complement regulator-acquiring surface proteins (BbCRASPs). (ox.ac.uk)
  • Loss of function mutations in the Complement Factor I gene lead to low levels of factor I which results in increased complement activity. (wikipedia.org)
  • At least 10 mutations in the CFI gene have been identified in people with complement factor I deficiency, a disorder characterized by immune system dysfunction. (medlineplus.gov)
  • The mutations result in abnormal, nonfunctional, or absent complement factor I. (medlineplus.gov)
  • The CFI gene mutations identified in this disorder result in an abnormal or nonfunctional version of complement factor I. The defective protein allows uncontrolled activation of the complement system. (medlineplus.gov)
  • Characterization of mutations in complement factor I (CFI) associated with hemolytic uremic syndrome. (medlineplus.gov)
  • Mapping the mutations onto the atomic structure of BbCRASP-1 reveals that, in contrast to earlier assumption, the C-terminal mutations act indirectly on FHL-1 and factor H binding, whilst the region 1 mutations map the site of direct complement regulator interaction. (ox.ac.uk)
  • Learn about the three pathways lead to complement activation and some of their key inhibitors. (abcam.com)
  • Each of these pathways uses different proteins. (medscape.com)
  • Activation of the complement pathways. (medscape.com)
  • Several complement inhibitors currently under development target various steps in the complement activation pathways. (justia.com)
  • C1 is the first molecule in the classical complement cascade and comprises C1q and two molecules of C1r and C1s respectively. (abcam.com)
  • The complement system functions as an interactive sequence, with one reaction leading to another in the form of a cascade. (medscape.com)
  • This invention relates to activation of the complement cascade in the body. (justia.com)
  • The alternative pathway of complement activation is in a constant state of low-level activation (known as tickover). (abcam.com)
  • Depending on the nature of complement activators, the classic pathway, the alternative pathway, or the more recently discovered lectin pathway is activated predominantly to produce C3 convertase. (medscape.com)
  • Factor I deficiency in turn leads to low levels of complement component 3 (C3), factor B, factor H and properdin in blood, due to unregulated activation of C3 convertase, and to low levels of IgG, due to loss of iC3b and C3dg production. (wikipedia.org)
  • It also accelerates the degradation of the C4bc2a complex (C3 convertase) by dissociating the complement fragment C2a. (lu.se)
  • In the first phase, a series of specific interactions leads to formation of intrinsic complement proteinase, termed C3 convertase. (medscape.com)
  • C3bBb complex then acts as the C3 convertase and generates more C3b through an amplification loop. (medscape.com)
  • Atypical hemolytic uremic syndrome is caused by complement overactivation. (wikipedia.org)
  • The lack (deficiency) of functional complement factor I protein allows uncontrolled activation of the complement system. (medlineplus.gov)
  • This condition, which may also occur in people with complement factor I deficiency, is characterized by kidney malfunction that can be serious or life-threatening. (medlineplus.gov)
  • We report 2 children with distinct causes of polycythemia, 1 from systemic capillary leak syndrome (SCLS) and the other from protein-losing enteropathy (PLE) caused by CD55 deficiency. (bvsalud.org)
  • Binding of factor H to C3b increases its inactivation by factor I. Properdin stabilizes it, preventing its inactivation by factors H and I. The alternate pathway does not result in a truly nonspecific activation of complement because it requires specific types of compounds for activation. (medscape.com)
  • Complement factor I, also known as C3b/C4b inactivator, is a protein that in humans is encoded by the CFI gene. (wikipedia.org)
  • 1996). Activation of C3 by the C3 convertases is a central amplification step in complement activation. (justia.com)
  • OBJECTIVES: This study aimed to evaluate the expression pattern of complement regulatory proteins (CRPs) CD46, CD59, and CD55 in HPV-positive (HPV+) & negative (HPV-) cervical cancer cell lines in search of a reliable differential biomarker. (bvsalud.org)
  • The functions of complement include the attraction of inflammatory cells, opsonization to promote phagocytosis, immune complex clearance and direct microbial killing through the formation of the membrane attack complex (MAC). (abcam.com)
  • Association of single nucleotide polymorphism in complement factor I gene with age-related macular degeneration]. (genscript.com)
  • The CFI gene provides instructions for making a protein called complement factor I. This protein helps regulate a part of the body's immune response known as the complement system. (medlineplus.gov)
  • The complement facts book , San Diego, 2000. (medscape.com)
  • Inappropriate activation of the complement system leads to tissue injury causing or aggravating various pathological conditions, such as autoimmune diseases, burn injuries, Alzheimer's disease, stroke and heart attack, among others (reviewed by Sahu and Lambris, 2000). (justia.com)
  • Then, factor I is cleaved by furin to yield the mature factor I protein, which is a disulfide-linked dimer of heavy chain (residues 19-335, 51 kDalton) and light chain (residues 340-583, 37 kDalton). (wikipedia.org)
  • C-reactive protein (CRP, not shown) leads to classic pathway activation analogous to lectin pathway activation by MBL and ficolins. (medscape.com)
  • Mannan-binding lectin (MBL) and MBL-associated serine proteases (MASPs) are involved in the initial step of the lectin pathway of complement activation. (abcam.com)
  • This work demonstrates that pathogens interact with complement regulators in ways that are distinct from the mechanisms used by the host and are thus obvious targets for drug design. (ox.ac.uk)
  • Previously, 3 regions including the C terminus were identified as putative contact sites for the two complement regulators by the pepspot analysis. (ox.ac.uk)
  • Single changes at 4 positions in region 1 either reduced (Lys136, Lys141, Glu147) or completely eliminated (Leu146) binding of both complement regulators. (ox.ac.uk)
  • Complement factor I and several related proteins protect healthy cells by preventing activation of the complement system when it is not needed. (medlineplus.gov)
  • Uncontrolled complement activation and resulting cell lysis is potentially dangerous for the host. (uams.edu)
  • Compstatin inhibits complement response by preventing the proteolytic activation of C3 (Sahu et al. (justia.com)
  • Because compstatin blocks this critical step of complement activation and because it is a small non-immunogenic peptide, compstatin has the potential to be developed into a therapeutic agent. (justia.com)
  • GenScript guarantees 100% sequence accuracy of all synthetic DNA constructs we deliver, but we do not guarantee protein expression in your experimental system. (genscript.com)
  • Invading trophoblast cells will encounter maternal complement system (C) in the decidua and in the intervillous space. (frontiersin.org)
  • The complement system is a heat-labile component of blood that confers bactericidal properties. (abcam.com)
  • The complement system is a group of proteins that work together to destroy foreign invaders (such as bacteria and viruses), trigger inflammation, and remove debris from cells and tissues. (medlineplus.gov)
  • The unregulated activity of the complement system decreases blood levels of another complement protein called C3, reducing the immune system's ability to fight infections. (medlineplus.gov)
  • The overactive complement system attacks certain kidney cells, which damages the kidneys and leads to a loss of protein in the urine (proteinuria). (medlineplus.gov)
  • The complement system is tightly regulated by inactivators that accelerate the decay of intermediates and certain cell surface receptors. (uams.edu)
  • Transcriptome characterization by RNA-Seq reveals the involvement of the complement components in noise-traumatized rat cochleae. (genscript.com)
  • The atomic structure of BbCRASP-1, the key FHL-1/FH-binding protein of B. burgdorferi, has recently been determined. (ox.ac.uk)
  • The BbCRASP-1 protein is the first bacterial factor H/FHL-1-binding protein for which the atomic structure has been solved. (ox.ac.uk)
  • The structure of C3c in complex with the complement inhibitor, compstatin, and use of this information for rational design or identification of complement-inhibiting drugs are disclosed. (justia.com)
  • These sequences represent the protein coding region of the Cfi cDNA ORF which is encoded by the open reading frame (ORF) sequence. (genscript.com)
  • Our analysis indicates that its protein topology apparently evolved to provide a high affinity interaction site for FH/FHL-1 and leads to an atomic-level hypothesis for the functioning of BbCRASP-1. (ox.ac.uk)
  • Protein expression is influenced by many factors that may vary between experiments or laboratories. (genscript.com)
  • This graph shows the total number of publications written about "Complement Inactivator Proteins" by people in UAMS Profiles by year, and whether "Complement Inactivator Proteins" was a major or minor topic of these publications. (uams.edu)
  • Below are the most recent publications written about "Complement Inactivator Proteins" by people in Profiles over the past ten years. (uams.edu)