Ruminant mammals of South America. They are related to camels.

An immunoglobulin fragment composed of one variable domain from an IMMUNOGLOBULIN HEAVY CHAIN or IMMUNOGLOBULIN LIGHT CHAIN.

Hoofed mammals with four legs, a big-lipped snout, and a humped back belonging to the family Camelidae.

Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).

A collection of cloned peptides, or chemically synthesized peptides, frequently consisting of all possible combinations of amino acids making up an n-amino acid peptide.

Staphylococcal toxoid refers to a bacterial toxin produced by Staphylococcus aureus that has been chemically modified to lose its toxicity, while retaining its antigenicity, used in the production of vaccines to induce immunity against Staphylococcus aureus infections.

The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.

The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kDa.

Disinfectant used in vapor form to sterilize vaccines, grafts, etc. The vapor is very irritating and the liquid form is carcinogenic.

A measure of the binding strength between antibody and a simple hapten or antigen determinant. It depends on the closeness of stereochemical fit between antibody combining sites and antigen determinants, on the size of the area of contact between them, and on the distribution of charged and hydrophobic groups. It includes the concept of "avidity," which refers to the strength of the antigen-antibody bond after formation of reversible complexes.

A form of antibodies consisting only of the variable regions of the heavy and light chains (FV FRAGMENTS), connected by a small linker peptide. They are less immunogenic than complete immunoglobulin and thus have potential therapeutic use.

That region of the immunoglobulin molecule that varies in its amino acid sequence and composition, and comprises the binding site for a specific antigen. It is located at the N-terminus of the Fab fragment of the immunoglobulin. It includes hypervariable regions (COMPLEMENTARITY DETERMINING REGIONS) and framework regions.

Three regions (CDR1; CDR2 and CDR3) of amino acid sequence in the IMMUNOGLOBULIN VARIABLE REGION that are highly divergent. Together the CDRs from the light and heavy immunoglobulin chains form a surface that is complementary to the antigen. These regions are also present in other members of the immunoglobulin superfamily, for example, T-cell receptors (RECEPTORS, ANTIGEN, T-CELL).

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.

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.

Antibodies produced by a single clone of cells.

The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.

Immunoglobulins produced in response to VIRAL ANTIGENS.

Immunoglobulins produced in a response to BACTERIAL ANTIGENS.

Univalent antigen-binding fragments composed of one entire IMMUNOGLOBULIN LIGHT CHAIN and the amino terminal end of one of the IMMUNOGLOBULIN HEAVY CHAINS from the hinge region, linked to each other by disulfide bonds. Fab contains the IMMUNOGLOBULIN VARIABLE REGIONS, which are part of the antigen-binding site, and the first IMMUNOGLOBULIN CONSTANT REGIONS. This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.

The PROTEIN SUBUNITS of the multimeric IMMUNOGLOBULIN proteins, such as IGA; IGD; IGE; IGG; and IGM. Included are the heavy and light chains which contain the specific ANTIGEN binding domains, as well as the accessory proteins that are part of the the secreted forms of IGM and IGA; (SECRETORY IGA).

Local surface sites on antibodies which react with antigen determinant sites on antigens (EPITOPES.) They are formed from parts of the variable regions of FAB FRAGMENTS.

Antibodies that reduce or abolish some biological activity of a soluble antigen or infectious agent, usually a virus.

The production of ANTIBODIES by proliferating and differentiated B-LYMPHOCYTES under stimulation by ANTIGENS.

Sites on an antigen that interact with specific antibodies.

The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.

Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.

Proteins prepared by recombinant DNA technology.

The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.

The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.

Protein modules with conserved ligand-binding surfaces which mediate specific interaction functions in SIGNAL TRANSDUCTION PATHWAYS and the specific BINDING SITES of their cognate protein LIGANDS.

Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.

The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).

Antibodies which react with the individual structural determinants (idiotopes) on the variable region of other antibodies.

The parts of a macromolecule that directly participate in its specific combination with another molecule.

The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.

Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.

The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Procedures by which protein structure and function are changed or created in vitro by altering existing or synthesizing new structural genes that direct the synthesis of proteins with sought-after properties. Such procedures may include the design of MOLECULAR MODELS of proteins using COMPUTER GRAPHICS or other molecular modeling techniques; site-specific mutagenesis (MUTAGENESIS, SITE-SPECIFIC) of existing genes; and DIRECTED MOLECULAR EVOLUTION techniques to create new genes.

Antibodies reactive with HIV ANTIGENS.

Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.

An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.

Immunoglobulins induced by antigens specific for tumors other than the normally occurring HISTOCOMPATIBILITY ANTIGENS.

The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.

Autoantibodies directed against various nuclear antigens including DNA, RNA, histones, acidic nuclear proteins, or complexes of these molecular elements. Antinuclear antibodies are found in systemic autoimmune diseases including systemic lupus erythematosus, Sjogren's syndrome, scleroderma, polymyositis, and mixed connective tissue disease.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.

Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.

The rate dynamics in chemical or physical systems.

A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.

Regions of AMINO ACID SEQUENCE similarity in the SRC-FAMILY TYROSINE KINASES that fold into specific functional tertiary structures. The SH1 domain is a CATALYTIC DOMAIN. SH2 and SH3 domains are protein interaction domains. SH2 usually binds PHOSPHOTYROSINE-containing proteins and SH3 interacts with CYTOSKELETAL PROTEINS.

Proteins found in any species of bacterium.

A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally being called a macroglobulin.

Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.

The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).

Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.

Immunoglobulins produced in a response to FUNGAL ANTIGENS.

The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.

The process by which two molecules of the same chemical composition form a condensation product or polymer.

Inbred BALB/c mice are a strain of laboratory mice that have been selectively bred to be genetically identical to each other, making them useful for scientific research and experiments due to their consistent genetic background and predictable responses to various stimuli or treatments.

Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.

A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.

The processes triggered by interactions of ANTIBODIES with their ANTIGENS.

Established cell cultures that have the potential to propagate indefinitely.

Antibodies, often monoclonal, in which the two antigen-binding sites are specific for separate ANTIGENIC DETERMINANTS. They are artificial antibodies produced by chemical crosslinking, fusion of HYBRIDOMA cells, or by molecular genetic techniques. They function as the main mediators of targeted cellular cytotoxicity and have been shown to be efficient in the targeting of drugs, toxins, radiolabeled haptens, and effector cells to diseased tissue, primarily tumors.

Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.

Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.

The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.

Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.

The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.

Antibodies that inhibit the reaction between ANTIGEN and other antibodies or sensitized T-LYMPHOCYTES (e.g., antibodies of the IMMUNOGLOBULIN G class that compete with IGE antibodies for antigen, thereby blocking an allergic response). Blocking antibodies that bind tumors and prevent destruction of tumor cells by CYTOTOXIC T-LYMPHOCYTES have also been called enhancing antibodies. (Rosen et al., Dictionary of Immunology, 1989)

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.

Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.

The characteristic 3-dimensional shape and arrangement of multimeric proteins (aggregates of more than one polypeptide chain).

Methods used for studying the interactions of antibodies with specific regions of protein antigens. Important applications of epitope mapping are found within the area of immunochemistry.

Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

A form of fluorescent antibody technique commonly used to detect serum antibodies and immune complexes in tissues and microorganisms in specimens from patients with infectious diseases. The technique involves formation of an antigen-antibody complex which is labeled with fluorescein-conjugated anti-immunoglobulin antibody. (From Bennington, Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)

The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.

The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.

Transport proteins that carry specific substances in the blood or across cell membranes.

Antibodies elicited in a different species from which the antigen originated. These antibodies are directed against a wide variety of interspecies-specific antigens, the best known of which are Forssman, Hanganutziu-Deicher (H-D), and Paul-Bunnell (P-B). Incidence of antibodies to these antigens--i.e., the phenomenon of heterophile antibody response--is useful in the serodiagnosis, pathogenesis, and prognosis of infection and latent infectious states as well as in cancer classification.

Antibodies that can catalyze a wide variety of chemical reactions. They are characterized by high substrate specificity and share many mechanistic features with enzymes.

Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.

Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.

Protein interaction domains of about 70-90 amino acid residues, named after a common structure found in PSD-95, Discs Large, and Zona Occludens 1 proteins. PDZ domains are involved in the recruitment and interaction of proteins, and aid the formation of protein scaffolds and signaling networks. This is achieved by sequence-specific binding between a PDZ domain in one protein and a PDZ motif in another protein.

The ability of a protein to retain its structural conformation or its activity when subjected to physical or chemical manipulations.

A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).

Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.

A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The sum of the weight of all the atoms in a molecule.

Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory IgA (IMMUNOGLOBULIN A, SECRETORY) is the main immunoglobulin in secretions.

Serum that contains antibodies. It is obtained from an animal that has been immunized either by ANTIGEN injection or infection with microorganisms containing the antigen.

The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.

Cells artificially created by fusion of activated lymphocytes with neoplastic cells. The resulting hybrid cells are cloned and produce pure MONOCLONAL ANTIBODIES or T-cell products, identical to those produced by the immunologically competent parent cell.

Antibodies from non-human species whose protein sequences have been modified to make them nearly identical with human antibodies. If the constant region and part of the variable region are replaced, they are called humanized. If only the constant region is modified they are called chimeric. INN names for humanized antibodies end in -zumab.

The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.

Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.

The relationships of groups of organisms as reflected by their genetic makeup.

Elements of limited time intervals, contributing to particular results or situations.

Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.

Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

Deletion of sequences of nucleic acids from the genetic material of an individual.

The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.

Autoantibodies directed against phospholipids. These antibodies are characteristically found in patients with systemic lupus erythematosus (LUPUS ERYTHEMATOSUS, SYSTEMIC;), ANTIPHOSPHOLIPID SYNDROME; related autoimmune diseases, some non-autoimmune diseases, and also in healthy individuals.

Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.

Serologic tests in which a positive reaction manifested by visible CHEMICAL PRECIPITATION occurs when a soluble ANTIGEN reacts with its precipitins, i.e., ANTIBODIES that can form a precipitate.

Histochemical localization of immunoreactive substances using labeled antibodies as reagents.

Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.

Substances that are recognized by the immune system and induce an immune reaction.

The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.

Immunologic techniques based on the use of: (1) enzyme-antibody conjugates; (2) enzyme-antigen conjugates; (3) antienzyme antibody followed by its homologous enzyme; or (4) enzyme-antienzyme complexes. These are used histologically for visualizing or labeling tissue specimens.

Substances elaborated by bacteria that have antigenic activity.

A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)

Partial immunoglobulin molecules resulting from selective cleavage by proteolytic enzymes or generated through PROTEIN ENGINEERING techniques.

The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.

The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)

A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

Glycoproteins found on the membrane or surface of cells.

Transfer of immunity from immunized to non-immune host by administration of serum antibodies, or transplantation of lymphocytes (ADOPTIVE TRANSFER).

Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.

Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.

A technique using antibodies for identifying or quantifying a substance. Usually the substance being studied serves as antigen both in antibody production and in measurement of antibody by the test substance.

Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.

Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.

The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.