Peptides: 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.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Peptide Library: 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.Antimicrobial Cationic Peptides: Small cationic peptides that are an important component, in most species, of early innate and induced defenses against invading microbes. In animals they are found on mucosal surfaces, within phagocytic granules, and on the surface of the body. They are also found in insects and plants. Among others, this group includes the DEFENSINS, protegrins, tachyplesins, and thionins. They displace DIVALENT CATIONS from phosphate groups of MEMBRANE LIPIDS leading to disruption of the membrane.Peptides, Cyclic: Peptides whose amino and carboxy ends are linked together with a peptide bond forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS. Some of them are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).Peptide Mapping: Analysis of PEPTIDES that are generated from the digestion or fragmentation of a protein or mixture of PROTEINS, by ELECTROPHORESIS; CHROMATOGRAPHY; or MASS SPECTROMETRY. The resulting peptide fingerprints are analyzed for a variety of purposes including the identification of the proteins in a sample, GENETIC POLYMORPHISMS, patterns of gene expression, and patterns diagnostic for diseases.Oligopeptides: Peptides composed of between two and twelve amino acids.Amino Acid Sequence: 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.Natriuretic Peptide, Brain: A PEPTIDE that is secreted by the BRAIN and the HEART ATRIA, stored mainly in cardiac ventricular MYOCARDIUM. It can cause NATRIURESIS; DIURESIS; VASODILATION; and inhibits secretion of RENIN and ALDOSTERONE. It improves heart function. It contains 32 AMINO ACIDS.Vasoactive Intestinal Peptide: A highly basic, 28 amino acid neuropeptide released from intestinal mucosa. It has a wide range of biological actions affecting the cardiovascular, gastrointestinal, and respiratory systems and is neuroprotective. It binds special receptors (RECEPTORS, VASOACTIVE INTESTINAL PEPTIDE).Calcitonin Gene-Related Peptide: Calcitonin gene-related peptide. A 37-amino acid peptide derived from the calcitonin gene. It occurs as a result of alternative processing of mRNA from the calcitonin gene. The neuropeptide is widely distributed in neural tissue of the brain, gut, perivascular nerves, and other tissue. The peptide produces multiple biological effects and has both circulatory and neurotransmitter modes of action. In particular, it is a potent endogenous vasodilator.Cell-Penetrating Peptides: Peptides that have the ability to enter cells by crossing the plasma membrane directly, or through uptake by the endocytotic pathway.Protein Binding: 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.Peptide Biosynthesis: The production of PEPTIDES or PROTEINS by the constituents of a living organism. The biosynthesis of proteins on RIBOSOMES following an RNA template is termed translation (TRANSLATION, GENETIC). There are other, non-ribosomal peptide biosynthesis (PEPTIDE BIOSYNTHESIS, NUCLEIC ACID-INDEPENDENT) mechanisms carried out by PEPTIDE SYNTHASES and PEPTIDYLTRANSFERASES. Further modifications of peptide chains yield functional peptide and protein molecules.Molecular Sequence Data: 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.Peptide YY: A 36-amino acid peptide produced by the L cells of the distal small intestine and colon. Peptide YY inhibits gastric and pancreatic secretion.Peptide Nucleic Acids: DNA analogs containing neutral amide backbone linkages composed of aminoethyl glycine units instead of the usual phosphodiester linkage of deoxyribose groups. Peptide nucleic acids have high biological stability and higher affinity for complementary DNA or RNA sequences than analogous DNA oligomers.Natriuretic Peptide, C-Type: A PEPTIDE of 22 amino acids, derived mainly from cells of VASCULAR ENDOTHELIUM. It is also found in the BRAIN, major endocrine glands, and other tissues. It shares structural homology with ATRIAL NATRIURETIC FACTOR. It has vasorelaxant activity thus is important in the regulation of vascular tone and blood flow. Several high molecular weight forms containing the 22 amino acids have been identified.Natriuretic Peptides: Peptides that regulate the WATER-ELECTROLYTE BALANCE in the body, also known as natriuretic peptide hormones. Several have been sequenced (ATRIAL NATRIURETIC FACTOR; BRAIN NATRIURETIC PEPTIDE; C-TYPE NATRIURETIC PEPTIDE).Protein Conformation: 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).Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Gastrin-Releasing Peptide: Neuropeptide and gut hormone that helps regulate GASTRIC ACID secretion and motor function. Once released from nerves in the antrum of the STOMACH, the neuropeptide stimulates release of GASTRIN from the GASTRIN-SECRETING CELLS.Protein Structure, Secondary: 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.Receptors, Formyl Peptide: A family of G-protein-coupled receptors that was originally identified by its ability to bind N-formyl peptides such as N-FORMYLMETHIONINE LEUCYL-PHENYLALANINE. Since N-formyl peptides are found in MITOCHONDRIA and BACTERIA, this class of receptors is believed to play a role in mediating cellular responses to cellular damage and bacterial invasion. However, non-formylated peptide ligands have also been found for this receptor class.Peptide PHI: A 27-amino acid peptide with histidine at the N-terminal and isoleucine amide at the C-terminal. The exact amino acid composition of the peptide is species dependent. The peptide is secreted in the intestine, but is found in the nervous system, many organs, and in the majority of peripheral tissues. It has a wide range of biological actions, affecting the cardiovascular, gastrointestinal, respiratory, and central nervous systems.Peptide Synthases: Ligases that catalyze the joining of adjacent AMINO ACIDS by the formation of carbon-nitrogen bonds between their carboxylic acid groups and amine groups.Peptide Hydrolases: Hydrolases that specifically cleave the peptide bonds found in PROTEINS and PEPTIDES. Examples of sub-subclasses for this group include EXOPEPTIDASES and ENDOPEPTIDASES.Receptors, Peptide: Cell surface receptors that bind peptide messengers with high affinity and regulate intracellular signals which influence the behavior of cells.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Atrial Natriuretic Factor: A potent natriuretic and vasodilatory peptide or mixture of different-sized low molecular weight PEPTIDES derived from a common precursor and secreted mainly by the HEART ATRIUM. All these peptides share a sequence of about 20 AMINO ACIDS.Epitopes: Sites on an antigen that interact with specific antibodies.Kinetics: The rate dynamics in chemical or physical systems.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Structure-Activity Relationship: 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.Protein PrecursorsTrypsin: A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Opioid Peptides: The endogenous peptides with opiate-like activity. The three major classes currently recognized are the ENKEPHALINS, the DYNORPHINS, and the ENDORPHINS. Each of these families derives from different precursors, proenkephalin, prodynorphin, and PRO-OPIOMELANOCORTIN, respectively. There are also at least three classes of OPIOID RECEPTORS, but the peptide families do not map to the receptors in a simple way.Intracellular Signaling Peptides and Proteins: Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.Peptide Hormones: Hormones synthesized from amino acids. They are distinguished from INTERCELLULAR SIGNALING PEPTIDES AND PROTEINS in that their actions are systemic.Protein Structure, Tertiary: 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.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Cloning, Molecular: 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.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization: A mass spectrometric technique that is used for the analysis of large biomolecules. Analyte molecules are embedded in an excess matrix of small organic molecules that show a high resonant absorption at the laser wavelength used. The matrix absorbs the laser energy, thus inducing a soft disintegration of the sample-matrix mixture into free (gas phase) matrix and analyte molecules and molecular ions. In general, only molecular ions of the analyte molecules are produced, and almost no fragmentation occurs. This makes the method well suited for molecular weight determinations and mixture analysis.Molecular Mimicry: The structure of one molecule that imitates or simulates the structure of a different molecule.Glucagon-Like Peptide 1: A peptide of 36 or 37 amino acids that is derived from PROGLUCAGON and mainly produced by the INTESTINAL L CELLS. GLP-1(1-37 or 1-36) is further N-terminally truncated resulting in GLP-1(7-37) or GLP-1-(7-36) which can be amidated. These GLP-1 peptides are known to enhance glucose-dependent INSULIN release, suppress GLUCAGON release and gastric emptying, lower BLOOD GLUCOSE, and reduce food intake.Escherichia coli: 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.Aptamers, Peptide: Peptide sequences, generated by iterative rounds of SELEX APTAMER TECHNIQUE, that bind to a target molecule specifically and with high affinity.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Molecular Weight: The sum of the weight of all the atoms in a molecule.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Cells, Cultured: 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.Cattle: 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.Receptors, Vasoactive Intestinal Peptide: Cell surface proteins that bind VASOACTIVE INTESTINAL PEPTIDE; (VIP); with high affinity and trigger intracellular changes which influence the behavior of cells.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Binding, Competitive: The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.Receptors, Atrial Natriuretic Factor: Cell surface proteins that bind ATRIAL NATRIURETIC FACTOR with high affinity and trigger intracellular changes influencing the behavior of cells. They contain intrinsic guanylyl cyclase activity.Amphibian Proteins: Proteins obtained from species in the class of AMPHIBIANS.Epitopes, T-Lymphocyte: Antigenic determinants recognized and bound by the T-cell receptor. Epitopes recognized by the T-cell receptor are often located in the inner, unexposed side of the antigen, and become accessible to the T-cell receptors after proteolytic processing of the antigen.Salivary Proteins and Peptides: Proteins and peptides found in SALIVA and the SALIVARY GLANDS. Some salivary proteins such as ALPHA-AMYLASES are enzymes, but their composition varies in different individuals.Amyloid beta-Peptides: Peptides generated from AMYLOID BETA-PEPTIDES PRECURSOR. An amyloid fibrillar form of these peptides is the major component of amyloid plaques found in individuals with Alzheimer's disease and in aged individuals with trisomy 21 (DOWN SYNDROME). The peptide is found predominantly in the nervous system, but there have been reports of its presence in non-neural tissue.Recombinant Fusion Proteins: 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.Antigen Presentation: The process by which antigen is presented to lymphocytes in a form they can recognize. This is performed by antigen presenting cells (APCs). Some antigens require processing before they can be recognized. Antigen processing consists of ingestion and partial digestion of the antigen by the APC, followed by presentation of fragments on the cell surface. (From Rosen et al., Dictionary of Immunology, 1989)Melitten: Basic polypeptide from the venom of the honey bee (Apis mellifera). It contains 26 amino acids, has cytolytic properties, causes contracture of muscle, releases histamine, and disrupts surface tension, probably due to lysis of cell and mitochondrial membranes.Sequence Alignment: 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 Processing, Post-Translational: Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Epitope Mapping: 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.Glucagon-Like Peptides: Peptides derived from proglucagon which is also the precursor of pancreatic GLUCAGON. Despite expression of proglucagon in multiple tissues, the major production site of glucagon-like peptides (GLPs) is the INTESTINAL L CELLS. GLPs include glucagon-like peptide 1, glucagon-like peptide 2, and the various truncated forms.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Defensins: Family of antimicrobial peptides that have been identified in humans, animals, and plants. They are thought to play a role in host defenses against infections, inflammation, wound repair, and acquired immunity.Cyanogen Bromide: Cyanogen bromide (CNBr). A compound used in molecular biology to digest some proteins and as a coupling reagent for phosphoroamidate or pyrophosphate internucleotide bonds in DNA duplexes.Dipeptides: Peptides composed of two amino acid units.Magainins: A class of antimicrobial peptides discovered in the skin of XENOPUS LAEVIS. They kill bacteria by permeabilizing cell membranes without exhibiting significant toxicity against mammalian cells.T-Lymphocytes, Cytotoxic: Immunized T-lymphocytes which can directly destroy appropriate target cells. These cytotoxic lymphocytes may be generated in vitro in mixed lymphocyte cultures (MLC), in vivo during a graft-versus-host (GVH) reaction, or after immunization with an allograft, tumor cell or virally transformed or chemically modified target cell. The lytic phenomenon is sometimes referred to as cell-mediated lympholysis (CML). These CD8-positive cells are distinct from NATURAL KILLER CELLS and NATURAL KILLER T-CELLS. There are two effector phenotypes: TC1 and TC2.Bacterial Proteins: Proteins found in any species of bacterium.Amino Acid Motifs: 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.HLA-A2 Antigen: A specific HLA-A surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-A*02 allele family.RNA, Messenger: 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.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Lipid Bilayers: Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.Receptors, Calcitonin Gene-Related Peptide: Cell surface proteins that bind CALCITONIN GENE-RELATED PEPTIDE with high affinity and trigger intracellular changes which influence the behavior of cells. CGRP receptors are present in both the CENTRAL NERVOUS SYSTEM and the periphery. They are formed via the heterodimerization of the CALCITONIN RECEPTOR-LIKE PROTEIN and RECEPTOR ACTIVITY-MODIFYING PROTEIN 1.Rabbits: 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.Cathelicidins: Antimicrobial cationic peptides with a highly conserved amino terminal cathelin-like domain and a more variable carboxy terminal domain. They are initially synthesized as preproproteins and then cleaved. They are expressed in many tissues of humans and localized to EPITHELIAL CELLS. They kill nonviral pathogens by forming pores in membranes.Membrane Proteins: 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.Endopeptidases: A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.Tandem Mass Spectrometry: A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Sequence Analysis, Protein: A process that includes the determination of AMINO ACID SEQUENCE of a protein (or peptide, oligopeptide or peptide fragment) and the information analysis of the sequence.Mutation: 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.Proteomics: The systematic study of the complete complement of proteins (PROTEOME) of organisms.Enzyme-Linked Immunosorbent Assay: 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.Mice, Inbred C57BLCarrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Drug Design: The molecular designing of drugs for specific purposes (such as DNA-binding, enzyme inhibition, anti-cancer efficacy, etc.) based on knowledge of molecular properties such as activity of functional groups, molecular geometry, and electronic structure, and also on information cataloged on analogous molecules. Drug design is generally computer-assisted molecular modeling and does not include pharmacokinetics, dosage analysis, or drug administration analysis.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Anti-Infective Agents: Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.HLA-A Antigens: Polymorphic class I human histocompatibility (HLA) surface antigens present on almost all nucleated cells. At least 20 antigens have been identified which are encoded by the A locus of multiple alleles on chromosome 6. They serve as targets for T-cell cytolytic responses and are involved with acceptance or rejection of tissue/organ grafts.Intercellular Signaling Peptides and Proteins: Regulatory proteins and peptides that are signaling molecules involved in the process of PARACRINE COMMUNICATION. They are generally considered factors that are expressed by one cell and are responded to by receptors on another nearby cell. They are distinguished from HORMONES in that their actions are local rather than distal.Mice, Inbred BALB CImmunodominant Epitopes: Subunits of the antigenic determinant that are most easily recognized by the immune system and thus most influence the specificity of the induced antibody.T-Lymphocytes: Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.Endorphins: One of the three major groups of endogenous opioid peptides. They are large peptides derived from the PRO-OPIOMELANOCORTIN precursor. The known members of this group are alpha-, beta-, and gamma-endorphin. The term endorphin is also sometimes used to refer to all opioid peptides, but the narrower sense is used here; OPIOID PEPTIDES is used for the broader group.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.Protein Folding: Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.DNA, Complementary: 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.Serine Endopeptidases: Any member of the group of ENDOPEPTIDASES containing at the active site a serine residue involved in catalysis.Bombesin: A tetradecapeptide originally obtained from the skins of toads Bombina bombina and B. variegata. It is also an endogenous neurotransmitter in many animals including mammals. Bombesin affects vascular and other smooth muscle, gastric secretion, and renal circulation and function.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Vaccines, Subunit: Vaccines consisting of one or more antigens that stimulate a strong immune response. They are purified from microorganisms or produced by recombinant DNA techniques, or they can be chemically synthesized peptides.Glucagon-Like Peptide 2: A 33-amino acid peptide derived from the C-terminal of PROGLUCAGON and mainly produced by the INTESTINAL L CELLS. It stimulates intestinal mucosal growth and decreased apoptosis of ENTEROCYTES. GLP-2 enhances gastrointestinal function and plays an important role in nutrient homeostasis.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Receptors, Bombesin: Cell surface proteins that bind bombesin or closely related peptides with high affinity and trigger intracellular changes influencing the behavior of cells. Gastrin- releasing peptide (GRP); GRP 18-27 (neuromedin C), and neuromedin B are endogenous ligands of bombesin receptors in mammals.Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.Cross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.Chromatography, Liquid: Chromatographic techniques in which the mobile phase is a liquid.Gastrointestinal Hormones: HORMONES secreted by the gastrointestinal mucosa that affect the timing or the quality of secretion of digestive enzymes, and regulate the motor activity of the digestive system organs.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Signal Transduction: 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.Spectrometry, Mass, Electrospray Ionization: A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.Amino Acid Substitution: The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.Antibodies: 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).Liposomes: Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.Transfection: 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.Lysine: An essential amino acid. It is often added to animal feed.Lymphocyte Activation: Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Proline: A non-essential amino acid that is synthesized from GLUTAMIC ACID. It is an essential component of COLLAGEN and is important for proper functioning of joints and tendons.Disulfides: Chemical groups containing the covalent disulfide bonds -S-S-. The sulfur atoms can be bound to inorganic or organic moieties.Blotting, Western: 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.Cysteine: A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.DNA: 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).H-2 Antigens: The major group of transplantation antigens in the mouse.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Thermodynamics: 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)beta-Defensins: DEFENSINS found mainly in epithelial cells.Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Peptide Biosynthesis, Nucleic Acid-Independent: The enzymatic synthesis of PEPTIDES without an RNA template by processes that do not use the ribosomal apparatus (RIBOSOMES).Mutagenesis, Site-Directed: Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Pyrrolidonecarboxylic Acid: A cyclized derivative of L-GLUTAMIC ACID. Elevated blood levels may be associated with problems of GLUTAMINE or GLUTATHIONE metabolism.Peptide T: N-(N-(N(2)-(N-(N-(N-(N-D-Alanyl L-seryl)-L-threonyl)-L-threonyl) L-threonyl)-L-asparaginyl)-L-tyrosyl) L-threonine. Octapeptide sharing sequence homology with HIV envelope protein gp120. It is potentially useful as antiviral agent in AIDS therapy. The core pentapeptide sequence, TTNYT, consisting of amino acids 4-8 in peptide T, is the HIV envelope sequence required for attachment to the CD4 receptor.Antibody Specificity: 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.Invertebrate Hormones: Hormones produced by invertebrates, usually insects, mollusks, annelids, and helminths.Tumor Cells, Cultured: Cells grown in vitro from neoplastic tissue. If they can be established as a TUMOR CELL LINE, they can be propagated in cell culture indefinitely.alpha-Defensins: DEFENSINS found in azurophilic granules of neutrophils and in the secretory granules of intestinal PANETH CELLS.Radioimmunoassay: Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.Cell Line, Tumor: A cell line derived from cultured tumor cells.Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Bacteriocins: Substances elaborated by specific strains of bacteria that are lethal against other strains of the same or related species. They are protein or lipopolysaccharide-protein complexes used in taxonomy studies of bacteria.Temperature: 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.Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.Chromatography, Affinity: A chromatographic technique that utilizes the ability of biological molecules to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Protein Engineering: 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.Solubility: The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Antigens, Neoplasm: Proteins, glycoprotein, or lipoprotein moieties on surfaces of tumor cells that are usually identified by monoclonal antibodies. Many of these are of either embryonic or viral origin.Amyloid: A fibrous protein complex that consists of proteins folded into a specific cross beta-pleated sheet structure. This fibrillar structure has been found as an alternative folding pattern for a variety of functional proteins. Deposits of amyloid in the form of AMYLOID PLAQUES are associated with a variety of degenerative diseases. The amyloid structure has also been found in a number of functional proteins that are unrelated to disease.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).CHO Cells: CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.Enkephalins: One of the three major families of endogenous opioid peptides. The enkephalins are pentapeptides that are widespread in the central and peripheral nervous systems and in the adrenal medulla.Adrenomedullin: A 52-amino acid peptide with multi-functions. It was originally isolated from PHEOCHROMOCYTOMA and ADRENAL MEDULLA but is widely distributed throughout the body including lung and kidney tissues. Besides controlling fluid-electrolyte homeostasis, adrenomedullin is a potent vasodilator and can inhibit pituitary ACTH secretion.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Glycopeptides: Proteins which contain carbohydrate groups attached covalently to the polypeptide chain. The protein moiety is the predominant group with the carbohydrate making up only a small percentage of the total weight.Substance P: An eleven-amino acid neurotransmitter that appears in both the central and peripheral nervous systems. It is involved in transmission of PAIN, causes rapid contractions of the gastrointestinal smooth muscle, and modulates inflammatory and immune responses.Isotope Labeling: Techniques for labeling a substance with a stable or radioactive isotope. It is not used for articles involving labeled substances unless the methods of labeling are substantively discussed. Tracers that may be labeled include chemical substances, cells, or microorganisms.Protease Inhibitors: Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).Trifluoroethanol: A non-aqueous co-solvent that serves as tool to study protein folding. It is also used in various pharmaceutical, chemical and engineering applications.Hydrogen Bonding: A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.Autoantigens: Endogenous tissue constituents that have the ability to interact with AUTOANTIBODIES and cause an immune response.Receptors, Cell Surface: Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.Chromatography, Ion Exchange: Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.Surface Plasmon Resonance: A biosensing technique in which biomolecules capable of binding to specific analytes or ligands are first immobilized on one side of a metallic film. Light is then focused on the opposite side of the film to excite the surface plasmons, that is, the oscillations of free electrons propagating along the film's surface. The refractive index of light reflecting off this surface is measured. When the immobilized biomolecules are bound by their ligands, an alteration in surface plasmons on the opposite side of the film is created which is directly proportional to the change in bound, or adsorbed, mass. Binding is measured by changes in the refractive index. The technique is used to study biomolecular interactions, such as antigen-antibody binding.Receptors, Vasoactive Intestinal Peptide, Type II: A pituitary adenylate cyclase-activating peptide receptor subtype found in LYMPHOCYTES. It binds both PACAP and VASOACTIVE INTESTINAL PEPTIDE and regulates immune responses.Spectroscopy, Fourier Transform Infrared: A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.PhosphopeptidesAlamethicin: A cyclic nonadecapeptide antibiotic that can act as an ionophore and is produced by strains of Trichoderma viride. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Phosphatidylglycerols: A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis.Arginine: An essential amino acid that is physiologically active in the L-form.DNA Primers: 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.Neuropeptide Y: A 36-amino acid peptide present in many organs and in many sympathetic noradrenergic neurons. It has vasoconstrictor and natriuretic activity and regulates local blood flow, glandular secretion, and smooth muscle activity. The peptide also stimulates feeding and drinking behavior and influences secretion of pituitary hormones.CD8-Positive T-Lymphocytes: A critical subpopulation of regulatory T-lymphocytes involved in MHC Class I-restricted interactions. They include both cytotoxic T-lymphocytes (T-LYMPHOCYTES, CYTOTOXIC) and CD8+ suppressor T-lymphocytes.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Enzyme Activation: Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.FMRFamide: A molluscan neuroactive peptide which induces a fast excitatory depolarizing response due to direct activation of amiloride-sensitive SODIUM CHANNELS. (From Nature 1995; 378(6558): 730-3)Combinatorial Chemistry Techniques: A technology, in which sets of reactions for solution or solid-phase synthesis, is used to create molecular libraries for analysis of compounds on a large scale.Solutions: The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)Cross-Linking Reagents: Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other.Nerve Tissue ProteinsProtein Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.Dimerization: The process by which two molecules of the same chemical composition form a condensation product or polymer.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Molecular Conformation: The characteristic three-dimensional shape of a molecule.Micelles: Particles consisting of aggregates of molecules held loosely together by secondary bonds. The surface of micelles are usually comprised of amphiphatic compounds that are oriented in a way that minimizes the energy of interaction between the micelle and its environment. Liquids that contain large numbers of suspended micelles are referred to as EMULSIONS.

The homeobox gene Pitx2: mediator of asymmetric left-right signaling in vertebrate heart and gut looping. (1/14921)

Left-right asymmetry in vertebrates is controlled by activities emanating from the left lateral plate. How these signals get transmitted to the forming organs is not known. A candidate mediator in mouse, frog and zebrafish embryos is the homeobox gene Pitx2. It is asymmetrically expressed in the left lateral plate mesoderm, tubular heart and early gut tube. Localized Pitx2 expression continues when these organs undergo asymmetric looping morphogenesis. Ectopic expression of Xnr1 in the right lateral plate induces Pitx2 transcription in Xenopus. Misexpression of Pitx2 affects situs and morphology of organs. These experiments suggest a role for Pitx2 in promoting looping of the linear heart and gut.  (+info)

Endocytosis: EH domains lend a hand. (2/14921)

A number of proteins that have been implicated in endocytosis feature a conserved protein-interaction module known as an EH domain. The three-dimensional structure of an EH domain has recently been solved, and is likely to presage significant advances in understanding molecular mechanisms of endocytosis.  (+info)

Sonic hedgehog signaling by the patched-smoothened receptor complex. (3/14921)

BACKGROUND: The Hedgehog (Hh) family of secreted proteins is involved in a number of developmental processes as well as in cancer. Genetic and biochemical data suggest that the Sonic hedgehog (Shh) receptor is composed of at least two proteins: the tumor suppressor protein Patched (Ptc) and the seven-transmembrane protein Smoothened (Smo). RESULTS: Using a biochemical assay for activation of the transcription factor Gli, a downstream component of the Hh pathway, we show here that Smo functions as the signaling component of the Shh receptor, and that this activity can be blocked by Ptc. The inhibition of Smo by Ptc can be relieved by the addition of Shh. Furthermore, oncogenic forms of Smo are insensitive to Ptc repression in this assay. Mapping of the Smo domains required for binding to Ptc and for signaling revealed that the Smo-Ptc interaction involves mainly the amino terminus of Smo, and that the third intracellular loop and the seventh transmembrane domain are required for signaling. CONCLUSIONS: These data demonstrate that Smo is the signaling component of a multicomponent Hh receptor complex and that Ptc is a ligand-regulated inhibitor of Smo. Different domains of Smo are involved in Ptc binding and activation of a Gli reporter construct. The latter requires the third intracellular loop and the seventh transmembrane domain of Smo, regions often involved in coupling to G proteins. No changes in the levels of cyclic AMP or calcium associated with such pathways could be detected following receptor activation, however.  (+info)

A Drosophila TNF-receptor-associated factor (TRAF) binds the ste20 kinase Misshapen and activates Jun kinase. (4/14921)

Two families of protein kinases that are closely related to Ste20 in their kinase domain have been identified - the p21-activated protein kinase (Pak) and SPS1 families [1-3]. In contrast to Pak family members, SPS1 family members do not bind and are not activated by GTP-bound p21Rac and Cdc42. We recently placed a member of the SPS1 family, called Misshapen (Msn), genetically upstream of the c-Jun amino-terminal (JNK) mitogen-activated protein (MAP) kinase module in Drosophila [4]. The failure to activate JNK in Drosophila leads to embryonic lethality due to the failure of these embryos to stimulate dorsal closure [5-8]. Msn probably functions as a MAP kinase kinase kinase kinase in Drosophila, activating the JNK pathway via an, as yet, undefined MAP kinase kinase kinase. We have identified a Drosophila TNF-receptor-associated factor, DTRAF1, by screening for Msn-interacting proteins using the yeast two-hybrid system. In contrast to the mammalian TRAFs that have been shown to activate JNK, DTRAF1 lacks an amino-terminal 'Ring-finger' domain, and overexpression of a truncated DTRAF1, consisting of only its TRAF domain, activates JNK. We also identified another DTRAF, DTRAF2, that contains an amino-terminal Ring-finger domain. Msn specifically binds the TRAF domain of DTRAF1 but not that of DTRAF2. In Drosophila, DTRAF1 is thus a good candidate for an upstream molecule that regulates the JNK pathway by interacting with, and activating, Msn. Consistent with this idea, expression of a dominant-negative Msn mutant protein blocks the activation of JNK by DTRAF1. Furthermore, coexpression of Msn with DTRAF1 leads to the synergistic activation of JNK. We have extended some of these observations to the mammalian homolog of Msn, Nck-interacting kinase (NIK), suggesting that TRAFs also play a critical role in regulating Ste20 kinases in mammals.  (+info)

Transformation mediated by RhoA requires activity of ROCK kinases. (5/14921)

BACKGROUND: The Ras-related GTPase RhoA controls signalling processes required for cytoskeletal reorganisation, transcriptional regulation, and transformation. The ability of RhoA mutants to transform cells correlates not with transcription but with their ability to bind ROCK-I, an effector kinase involved in cytoskeletal reorganisation. We used a recently developed specific ROCK inhibitor, Y-27632, and ROCK truncation mutants to investigate the role of ROCK kinases in transcriptional activation and transformation. RESULTS: In NIH3T3 cells, Y-27632 did not prevent the activation of serum response factor, transcription of c-fos or cell cycle re-entry following serum stimulation. Repeated treatment of NIH3T3 cells with Y-27632, however, substantially disrupted their actin fibre network but did not affect their growth rate. Y-27632 blocked focus formation by RhoA and its guanine-nucleotide exchange factors Dbl and mNET1. It did not affect the growth rate of cells transformed by Dbl and mNET1, but restored normal growth control at confluence and prevented their growth in soft agar. Y-27632 also significantly inhibited focus formation by Ras, but had no effect on the establishment or maintenance of transformation by Src. Furthermore, it significantly inhibited anchorage-independent growth of two out of four colorectal tumour cell lines. Consistent with these data, a truncated ROCK derivative exhibited weak ability to cooperate with activated Raf in focus formation assays. CONCLUSIONS: ROCK signalling is required for both the establishment and maintenance of transformation by constitutive activation of RhoA, and contributes to the Ras-transformed phenotype. These observations provide a potential explanation for the requirement for Rho in Ras-mediated transformation. Moreover, the inhibition of ROCK kinases may be of therapeutic use.  (+info)

Decreased expression of the pro-apoptotic protein Par-4 in renal cell carcinoma. (6/14921)

Par-4 is a widely expressed leucine zipper protein that confers sensitization to apoptosis induced by exogenous insults. Because the expression of genes that promote apoptosis may be down-regulated during tumorigenesis, we sought to examine the expression of Par-4 in human tumors. We present here evidence that Par-4 protein levels were severely decreased in human renal cell carcinoma specimens relative to normal tubular cells. Replenishment of Par-4 protein levels in renal cell carcinoma cell lines conferred sensitivity to apoptosis. Because apoptosis may serve as a defense mechanism against malignant transformation or progression, decreased expression of Par-4 may contribute to the pathophysiology of renal cell carcinoma.  (+info)

Activation of Src in human breast tumor cell lines: elevated levels of phosphotyrosine phosphatase activity that preferentially recognizes the Src carboxy terminal negative regulatory tyrosine 530. (7/14921)

Elevated levels of Src kinase activity have been reported in a number of human cancers, including colon and breast cancer. We have analysed four human breast tumor cell lines that exhibit high levels of Src kinase activity, and have determined that these cell lines also exhibit a high level of a phosphotyrosine phosphatase activity that recognizes the Src carboxy-terminal P-Tyr530 negative regulatory site. Total Src kinase activity in these cell lines is elevated as much as 30-fold over activity in normal control cells and specific activity is elevated as much as 5.6-fold. When the breast tumor cells were grown in the presence of the tyrosine phosphatase inhibitor vanadate, Src kinase activity was reduced in all four breast tumor cell lines, suggesting that Src was being activated by a phosphatase which could recognize the Tyr530 negative regulatory site. In fractionated cell extracts from the breast tumor cells, we found elevated levels of a membrane associated tyrosine phosphatase activity that preferentially dephosphorylated a Src family carboxy-terminal phosphopeptide containing the regulatory tyrosine 530 site. Src was hypophosphorylated in vivo at tyrosine 530 in at least two of the tumor cell lines, further suggesting that Src was being activated by a phosphatase in these cells. In preliminary immunoprecipitation and antibody depletion experiments, we were unable to correlate the major portion of this phosphatase activity with several known phosphatases.  (+info)

Gadd45, a p53-responsive stress protein, modifies DNA accessibility on damaged chromatin. (8/14921)

This report demonstrates that Gadd45, a p53-responsive stress protein, can facilitate topoisomerase relaxing and cleavage activity in the presence of core histones. A correlation between reduced expression of Gadd45 and increased resistance to topoisomerase I and topoisomerase II inhibitors in a variety of human cell lines was also found. Gadd45 could potentially mediate this effect by destabilizing histone-DNA interactions since it was found to interact directly with the four core histones. To evaluate this possibility, we investigated the effect of Gadd45 on preassembled mononucleosomes. Our data indicate that Gadd45 directly associates with mononucleosomes that have been altered by histone acetylation or UV radiation. This interaction resulted in increased DNase I accessibility on hyperacetylated mononucleosomes and substantial reduction of T4 endonuclease V accessibility to cyclobutane pyrimidine dimers on UV-irradiated mononucleosomes but not on naked DNA. Both histone acetylation and UV radiation are thought to destabilize the nucleosomal structure. Hence, these results imply that Gadd45 can recognize an altered chromatin state and modulate DNA accessibility to cellular proteins.  (+info)

  • Immunomodulatory signals have long been implicated as key regulators of bone metabolism. (
  • Numerous immunomodulatory signals are concurrently involved in the regulation of bone metabolism and vice versa bone-derived proteins, such as osteopontin, may have immunomodulatory effects ( 5 ). (
  • Agilent cell metabolism assays detect discrete changes in cell bioenergetics in real time, providing a window into the critical functions that provide ATP, the energy that cells need for activation, signaling, proliferation, and biosynthesis. (
  • To evaluate intracellular calcium mobilization, 8-( N,N -diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) or heparin was coadministered with AVP. (
  • Approximately two thirds of the change in vascular tone is due to inositol 1,4,5-trisphosphate-mediated calcium mobilization from intracellular sources sensitive to TMB-8 and heparin. (
  • It is also a major storage site for calcium, phosphorus, and proteins, which are released upon osteoclastic resorption. (
  • A so-called signaling protein and "calcium sensor," calmodulin gives start and stop signals for a great number of intracellular activities by binding and releasing other proteins. (
  • Professor Matthias Rief and colleagues at the Technische Universitaet Muenchen had previously shown that they could fix a single calmodulin molecule between a surface and the cantilever tip of a specially built atomic-force microscope, expose it to calcium ions in solution, induce peptide binding and unbinding, and measure changes in the molecule's mechanical properties as it did its work. (
  • Ghrelin is a newly discovered peptide that is released from the stomach and from neurons in the hypothalamic arcuate nucleus (ARC) and potently stimulates growth hormone release and food intake. (
  • However, the intracellular signaling for ghrelin's orexigenic action in the effector neurons is not well understood. (
  • Key to this regulatory function is the melanocortin system, which consists of two functionally antagonistic neuronal populations - one subset of neurons expresses the orexigenic neuropeptides agouti-related peptide (AgRP) and neuropeptide Y (NPY), the second subset expresses the anorexigenic peptides proopiomelanocortin (POMC) and cocaine and amphetamine regulated transcript (CART). (
  • These domains define two families of adaptor proteins which function in membrane traffic and whose interaction with membranes is regulated, in part, by phosphoinositides. (
  • Membrane regulatory proteins, such as CD46, CD55, and CD59, prevent excess complement activation and to protect cells from damage. (
  • Comparison of Schwannomin with other proteins shows similarities to proteins that connect the cytoskeleton to the cell membrane. (
  • In contrast, precursors with YSIRK-G/S signal peptides are secreted into the cross-wall, a membrane enclosed compartment for the de novo synthesis of peptidoglycan that separates daughter cells during division ( 14 ). (
  • Ectopic expression of the protein disrupts the structure of the Golgi, suggesting that N4WBP5 forms part of a family of integral Golgi membrane proteins. (
  • C-peptide is able to protect against tumor necrosis factor-alpha- (TNF-a) induced proximal tubular cells toxicity. (
  • These proteins are frequently altered in neoplastic cells and have traditionally been considered as tumor suppressors. (
  • This peptide is thought to have a tumor-suppressive function. (
  • Mutations of NF II is presumed to result in either a failure to synthesize Merlin or the production of a defective peptide that lacks the normal tumor-suppressive effect. (
  • Deletions, too, in the NH2-terminal domain of merlin proteins have been associated with early tumor onset and poor prognosis in affected patients. (
  • On the other hand, heat shock protein 70 has been found to be largely associated with the establishment of anti-tumor activities offered by hyperthermia treated tumor cells. (
  • During tumor metastasis, integrin-mediated cell adhesion to and migration on the ECM proteins are required for cancer cell survival and adaptation to the new microenvironment. (
  • Hippo signaling is not solely involved in regulating "classic" tumor characteristics such as cell proliferation, survival and growth, but is also diversely involved in cell-autonomous and non-cell-autonomous differentiation, migration and organ size control. (
  • The SET protein is a promising drug target in cancer therapy, because of its ability to inhibit the function of the tumor suppressor gene protein phosphatase 2A (PP2A). (
  • Motoneurons resistant to Fas activation expressed high levels of FLICE-inhibitory protein (FLIP), an endogenous inhibitor of caspase-8 activation. (
  • Here, we have isolated a 12-aa peptide from soybean ( Glycine max ) leaves that causes a pH increase of soybean suspension-cultured cell media within 10 min at low nanomolar concentrations, a response that is typical of other endogenous peptide elicitors and pathogen-derived elicitors. (
  • These elicitors can be of a heterogeneous nature, such as cutin monomers or cell wall fragments of various sizes ( 2 - 4 ), which exist in all plant species, or they can be a more specific, fine-tuned signal, such as endogenous peptide signals, which may be limited to a single phylogenetic family, coevolving with a specific predator ( 5 - 7 ). (
  • Relatively few endogenous peptide defense signals have been isolated thus far. (
  • These peptides are used as an internal calibration curve to accurately quantify endogenous peptides and corresponding proteins in a pooled platelet reference sample by nanoLC-MS/MS with parallel reaction monitoring. (
  • Biosynthesis of lanthionine-constrained peptides exploiting engineered Gram-positive or Gram-negative bacteria that contain lanthionine-introducing enzymes constitutes a convenient method for discovery of lanthionine-stabilized GPCR agonists. (
  • This study has now for the first time demonstrated specifically that Ga* proteins are activated by C-peptide binding to a GPCR. (
  • Filamins are large proteins that cross-link actin filaments and connect to other cellular components. (
  • A variety of protein complexes have previously been described for the human malaria parasite Plasmodium falciparum , like the actin-myosin motor complex enabling gliding motility of the invasive stages. (
  • Synthetic peptide (LIPQQ(pS)INEAI[K]) corresponding to amino acids 826-836 of rat mature GluR1 (Accession No. P19490), with a phosphorylated serine at position 831, and a lysine added to the C-terminus for conjugation. (
  • There were no significant changes in intracellular [Ca2ⴙ] when platelets were treated with aPL and low doses of thrombin. (
  • The contents of the epididymal lumen are constantly changing due to ion transport across the epithelium and protein secretion into the epididymal lumen. (
  • The insect host defense involves synthesis of antimicrobial peptides by the fat body and secretion into the hemolymph ( 1 ). (
  • W. J. Phillips and R. A. Cerione, "A C-terminal peptide of bovine rhodopsin binds to the transducin α -subunit and facilitates its activation," Biochemical Journal , vol. 299, no. 2, pp. 351-357, 1994. (
  • Fragment containing α 1 1.2-subunit (745-892) was subcloned in pGBKT7 vector (Clontech Laboratories, Palo Alto, CA) as a Myc-tagged protein. (
  • Activation and deactivation of small GTPases can be regarded as occurring in a cycle, between the GTP-bound and GDP-bound form, regulated by other regulatory proteins. (
  • Intracellular events in platelet activation induced by antiphospholipid antibodies in the presence of low doses of thrombin. (
  • The intracellular events involved in aPL-mediated platelet activation are not fully understood and are therefore the subject of this study. (
  • GW9662, an irreversible PPARy antagonist, blocked PPARy activation by ciglitazone, but had no effect on C-peptide-stimulated PPARy activity. (
  • The initial expansion of naive autoreactive T cells requires activation of the TCR by MHC-bound peptides or CD1-bound lipids/glycolipids. (
  • The protein functions to initiate or augment the early phase of T-cell activation, and may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system. (
  • The most potent grafted MCoTI-II peptide inhibited lipopolysaccharide (LPS)-mediated activation of NF-B in murine macrophages. (
  • The activation of Ras is induced by a number of peptide growth factors. (
  • Abatacept binds CD80 and CD86 on antigen presenting cells (APCs), blocking interaction with CD28 on T lymphocytes, which initiates a co-stimulatory signal required for full activation of T lymphocytes. (
  • Using recombinant fusion proteins, we show that MARCKS, but not the ENaC subunits, are a substrate of calpain-2 in the presence of Ca Pharmacological inhibition of calpain-2 alters MARCKS protein expression in light-density sucrose gradient fractions from cell lysates of mouse cortical collecting duct cells. (
  • Plant Cell Wall Proteins: A Large Body of Data, but What about Runaways? (
  • Plant cell wall proteomics is a tricky field of research, since proteins are not only minor components of plant cell walls, but are also trapped in complex networks of polysaccharides with which they can interact. (
  • Cell wall proteins (CWPs) are the "blue collar workers," modifying cell wall components and customizing them to confer appropriate properties to cell walls [ 6 ]. (
  • Thus, a large variety of proteins are present in cell walls [ 10 ]. (
  • Ab fragments expressed in the appropriate cell compartment may also help to elucidate the functions of a protein of interest. (
  • Members of this family share a common protein fold and have diverse functions, such as cell adhesion, cell-cell signalling, glycoprotein turnover, and roles in inflammation and immune response. (
  • In dividing Drosophila neural progenitors the apical-basal orientation of the mitotic spindle, the basal cortical localization of the cell fate determinants Numb and/or Prospero as well as the coordination of these events are mediated by several proteins which include Bazooka (Baz), Inscuteable (Insc) and Partner of Inscuteable (Pins) which localize as an apical cortical complex starting at interphase. (
  • Also, these findings provide mechanistic insight into how GV1001 peptide causes anti-inflammatory actions in LPS-stimulated pulpitis without significantly affecting cell viability. (
  • Dense granule (GRA) proteins are secreted, at high levels shortly after host cell invasion and then constitutively at a lower level thereafter. (
  • These signals include bacterial peptide fragments, such as flg22 and elf18 ( 8 , 9 ), fungal peptide elicitors, such as Pep13, AVR9, and elicitins ( 10 - 12 ), chitin fragments from fungal cell walls ( 13 ), and the heptaglucoside elicitor from the oomycete Phytophtora megasperma ( 3 ). (
  • C-peptide was found to be a functional mitogen in this cell type stimulating significantly increased cell proliferation. (
  • Stimulation with 300ng/ml TNF-a for 24 hours resulted in significant reduction of cell viability which was reversed by pretreatment with C-peptide. (
  • C-peptide increased [35S]-GTPyS binding to Ga* in OK cell membranes. (
  • The main argument of this book is that cell signalling via nerves, hormones, local mediators and growth factors are not distinct phenomena, but branches of one general mechanism and should therefore be studied in an integrated manner. (
  • Introduction - cell-to-cell signalling by bridges: why do cells need to communicate? (
  • This is the first report on a plasmodial WD40-repeat protein associating with cell adhesion proteins. (
  • Protein complexes are formed by two or more non-covalently bound proteins mutually supportive in distinct cell functions. (
  • Protein complexes are crucial for most cell biological processes and among others function in establishing cell-cell contacts. (
  • Integrins interact with extracellular matrix (ECM) and deliver intracellular signaling for cell proliferation, survival, and motility. (
  • Each cell within plants, animals, and fungi, contains a protein skeleton that helps to stabilize it. (
  • We demonstrate that protein A of Staphylococcus aureus , a B cell superantigen, is released with peptidoglycan linked to its C terminus. (
  • Staphylococcal protein A (SpA) is anchored to the cell wall envelope of Staphylococcus aureus by sortase A, which links the threonyl (T) of its C-terminal LPXTG motif to peptidoglycan cross-bridges (i.e. (
  • Cell wall-anchored surface proteins are synthesized as precursors with N-terminal signal peptides and C-terminal LPXTG motif sorting signals ( 9 ). (
  • Events within the cell that occur in response to a signal, different cell types can respond differently to the same signal. (
  • Signals released from a cell have an effect on neighboring cells. (
  • The pancreatic β-cell is a typical endocrine cell in which exocytosis of insulin-containing vesicles is regulated by a variety of intracellular signals. (
  • In an attempt to bridge this gap and to reach into the concentration range of the desirable tissue-derived proteins in plasma, we have developed methods for high throughput and in depth analysis of cell surface proteins, secreted proteins, and plasma proteins. (
  • These approaches are based on the observation that most cell surface and secreted proteins are glycosylated and that disease-associated glycoproteins, either secreted by cells, shed from their surfaces, or otherwise released, are likely to enter into the blood stream and thus represent a rich source of potential disease markers. (
  • The grafted MCoTI-II peptides were cytotoxic to a cancer cell line and showed high stability in human serum. (
  • Thus, Ras proteins are critical in stimulating cell growth and division. (
  • Intracellular Signaling Peptides and Proteins" is a descriptor in the National Library of Medicine's controlled vocabulary thesaurus, MeSH (Medical Subject Headings) . (
  • Seven distinct antimicrobial peptides (plus isoforms) have been described in Drosophila . (
  • Rief and Junker used mechanical force - actually pulling on complexes of calmodulin and the target peptides at rates of 1 nanometer per second or less - to slow down the processes to observable time scales and to clearly separate the individual unbinding steps. (
  • They recognize their target peptides in extended β -sheet conformations with very regular binding topologies. (
  • Amyloid-β peptide induces mitochondrial dysfunction by inhibition of preprotein maturation. (
  • The replicase polyprotein of coronaviruses is a multifunctional protein: it contains the activities necessary for the transcription of negative stranded RNA, leader RNA, subgenomic mRNAs and progeny virion RNA as well as proteinases responsible for the cleavage of the polyprotein into functional products. (
  • It is present at the NH2-terminus of proteins that often contain consensus sequences for binding to clathrin coat components and their accessory factors, and therefore function as endocytic adaptors. (