Canadian Medical Guide > Chemicals and Drugs > Amino Acids, Peptides, and Proteins > Proteins Terms and Definitions




Proteins

Medical Definition: Polymers of amino acids linked by peptide bonds. The specific sequence of amino acids determines the shape and function of the protein.
Guide Notes: GEN only: prefer specific proteins or specific precoord organ /proteins (EYE PROTEINS, etc.) or microbial proteins (BACTERIAL PROTEINS, etc.) & others; /biosyn: consider also PEPTIDE CHAIN INITIATION & related terms in Cat G5; DIETARY PROTEINS is also ava
Also Called: Gene Products, Protein
Proteins Categories.
Canadian Medical Guide Definition Albumins - Water-soluble proteins found in egg whites, blood, lymph, and other tissues and fluids. They coagulate upon heating.
Canadian Medical Guide Definition Algal Proteins - Proteins found in any species of algae.
Canadian Medical Guide Definition Amphibian Proteins - Proteins obtained from species in the class of AMPHIBIA.
Canadian Medical Guide Definition Antifreeze Proteins - Proteins that bind to ice and modify the growth of ice crystals. They perform a cryoprotective role in a variety of organisms.
Canadian Medical Guide Definition Apoproteins
Canadian Medical Guide Definition Aprotinin - A single-chain polypeptide derived from bovine tissues consisting of 58 amino-acid residues. It is an inhibitor of proteolytic enzymes including chymotrypsin, kallikrein, plasmin, and trypsin. It is used in the treatment of hemorrhage associated with raised plasma concentrations of plasmin. It is also used to reduce blood loss and transfusion requirements in patients at high risk of major blood loss during and following open heart surgery with extracorporeal circulation. (Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Englewood, CO, 1995)
Canadian Medical Guide Definition Archaeal Proteins - Proteins found in any species of archaeon.
Canadian Medical Guide Definition Avian Proteins - Proteins obtained from species of BIRDS.
Canadian Medical Guide Definition Bacterial Proteins - Proteins found in any species of bacterium.
Canadian Medical Guide Definition Blood Proteins - Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.
Canadian Medical Guide Definition Carrier Proteins - Transport proteins that carry specific substances in the blood or across cell membranes.
Canadian Medical Guide Definition Cell Cycle Proteins - Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and phosphoprotein phosphatases (PHOSPHOPROTEIN PHOSPHATASE) as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.
Canadian Medical Guide Definition Cerebrospinal Fluid Proteins - Proteins in the cerebrospinal fluid, normally albumin and globulin present in the ratio of 8 to 1. Increases in protein levels are of diagnostic value in neurological diseases. (Brain and Bannister's Clinical Neurology, 7th ed, p221)
Canadian Medical Guide Definition Colipases - Colipase I and II, consisting of 94-95 and 84-85 amino acid residues, respectively, have been isolated from porcine pancreas. Their role is to prevent the inhibitory effect of bile salts on the lipase-catalyzed intraduodenal hydrolysis of dietary long-chain triglycerides.
Canadian Medical Guide Definition Contractile Proteins - Proteins which participate in contractile processes. They include MUSCLE PROTEINS as well as those found in other cells and tissues. In the latter, these proteins participate in localized contractile events in the cytoplasm, in motile activity, and in cell aggregation phenomena.
Canadian Medical Guide Definition Cystatins - A homologous group of endogenous cysteine proteinase inhibitors. Four distinct families are recognized within the cystatin superfamily: cystatin B or stefins; cystatin C or post-gamma-globulin; egg-white or chicken cystatin; and kininogen cystatin. The cystatins inhibit most Cysteine Endopeptidases of the papain type, and other peptidases which have a sulfhydryl group at the active site.
Canadian Medical Guide Definition Cytoskeletal Proteins - Major constituent of the cytoskeleton found in the cytoplasm of eukaryotic cells. They form a flexible framework for the cell, provide attachment points for organelles and formed bodies, and make communication between parts of the cell possible.
Canadian Medical Guide Definition Dental Enamel Proteins - The proteins that are part of the dental enamel matrix.
Canadian Medical Guide Definition Dietary Proteins - Proteins obtained from foods. They are the main source of the essential amino acids.
Canadian Medical Guide Definition DNA-Binding Proteins - 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.
Canadian Medical Guide Definition Egg Proteins - Proteins which are found in eggs or ova from any species.
Canadian Medical Guide Definition Epididymal Secretory Proteins - Proteins secreted by the epididymal epithelium. These proteins are both tissue- and species-specific. They are important molecular agents in the process of sperm maturation.
Canadian Medical Guide Definition Eye Proteins
Canadian Medical Guide Definition Fetal Proteins
Canadian Medical Guide Definition Fish Proteins - Proteins obtained from species of fish (FISHES).
Canadian Medical Guide Definition Flavoproteins
Canadian Medical Guide Definition Fungal Proteins - Proteins found in any species of fungus.
Canadian Medical Guide Definition Globulins
Canadian Medical Guide Definition GTP-Binding Protein Regulators - Proteins that regulate the signaling activity of GTP-BINDING PROTEINS. They are divided into three categories depending upon whether they stimulate GTPase activity (GTPASE-ACTIVATING PROTEINS), inhibit release of GDP; (GUANINE NUCLEOTIDE DISSOCIATION INHIBITORS); or exchange GTP for GDP; (GUANINE NUCLEOTIDE EXCHANGE FACTORS).
Canadian Medical Guide Definition Heat-Shock Proteins - Proteins which are synthesized in eukaryotic organisms and bacteria in response to hyperthermia and other environmental stresses. They increase thermal tolerance and perform functions essential to cell survival under these conditions.
Canadian Medical Guide Definition Helminth Proteins - Proteins found in any species of helminth.
Canadian Medical Guide Definition Hemeproteins - Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)
Canadian Medical Guide Definition Insect Proteins - Proteins found in any species of insect.
Canadian Medical Guide Definition Iodoproteins
Canadian Medical Guide Definition Iron-Regulatory Proteins - Proteins that regulate cellular and organismal iron homeostasis. They play an important biological role by maintaining iron levels that are adequate for metabolic need, but below the toxicity theshold.
Canadian Medical Guide Definition LDL-Receptor Related Proteins - A family of proteins that share sequence similarity with the low density lipoprotein receptor (RECEPTORS, LDL).
Canadian Medical Guide Definition Lectins - Proteins that share the common characteristic of binding to carbohydrates. Some ANTIBODIES and carbohydrate-metabolizing proteins (ENZYMES) also bind to carbohydrates, however they are not considered lectins. PLANT LECTINS are carbohydrate-binding proteins that have been primarily identified by their hemagglutinating activity (HEMAGGLUTININS). However, a variety of lectins occur in animal species where they serve diverse array of functions through specific carbohydrate recognition.
Canadian Medical Guide Definition Luminescent Proteins - Proteins which are involved in the phenomenon of light emission in living systems. Included are the "enzymatic" and "non-enzymatic" types of system with or without the presence of oxygen or co-factors.
Canadian Medical Guide Definition 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.
Canadian Medical Guide Definition Metalloproteins - Proteins that have one or more tightly bound metal ions forming part of their structure. (Dorland, 28th ed)
Canadian Medical Guide Definition Mitochondrial Proteins - Proteins encoded by the mitochondrial genome or proteins encoded by the nuclear genome that are imported to and resident in the MITOCHONDRIA.
Canadian Medical Guide Definition Molecular Chaperones - A family of cellular proteins that mediate the correct assembly or disassembly of other polypeptides, and in some cases their assembly into oligomeric structures, but which are not components of those final structures. It is believed that chaperone proteins assist polypeptides to self-assemble by inhibiting alternative assembly pathways that produce nonfunctional structures. Some classes of molecular chaperones are the nucleoplasmins, the CHAPERONINS, the HEAT-SHOCK PROTEINS 70, and the HEAT-SHOCK PROTEINS 90.
Canadian Medical Guide Definition Neoplasm Proteins - Proteins whose abnormal expression (gain or loss) are associated with the development, growth, or progression of NEOPLASMS. Some neoplasm proteins are tumor antigens (ANTIGENS, NEOPLASM), i.e. they induce an immune reaction to their tumor. Many neoplasm proteins have been characterised and are used as tumor markers (TUMOR MARKERS, BIOLOGICAL) when they are detectable in cells and body fluids as monitors for the presence or growth of tumors. Abnormal expression of ONCOGENE PROTEINS is involved in neoplastic transformation, whereas the loss of expression of TUMOR SUPPRESSOR PROTEINS is involved with the loss of growth control and progression of the neoplasm.
Canadian Medical Guide Definition Nerve Tissue Proteins
Canadian Medical Guide Definition Nuclear Proteins - 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.
Canadian Medical Guide Definition Nucleoproteins - Proteins conjugated with nucleic acids.
Canadian Medical Guide Definition Oxidative Phosphorylation Coupling Factors
Canadian Medical Guide Definition Peptones - Derived proteins or mixtures of cleavage products produced by the partial hydrolysis of a native protein either by an acid or by an enzyme. Peptones are readily soluble in water, and are not precipitable by heat, by alkalis, or by saturation with ammonium sulfate. (Dorland, 28th ed)
Canadian Medical Guide Definition Phosphoproteins
Canadian Medical Guide Definition Photoreceptors, Microbial - Light absorbing proteins and protein prosthetic groups found in certain microrganisms. Some microbial photoreceptors initiate specific chemical reactions which signal a change in the environment, while others generate energy by pumping specific ions across a cellular membrane.
Canadian Medical Guide Definition Plant Proteins - Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.
Canadian Medical Guide Definition Polyproteins - Proteins which are synthesized as a single polymer and then cleaved into several distinct proteins.
Canadian Medical Guide Definition Pregnancy Proteins - Proteins produced by organs of the mother or the PLACENTA during PREGNANCY. These proteins may be pregnancy-specific (present only during pregnancy) or pregnancy-associated (present during pregnancy or under other conditons such as hormone therapy or certain malignancies.)
Canadian Medical Guide Definition Prions - Small proteinaceous infectious particles which resist inactivation by procedures that modify NUCLEIC ACIDS and contain an abnormal isoform of a cellular protein which is a major and necessary component. The abnormal (scrapie) isoform is PrPSc (PRPSC PROTEINS) and the cellular isoform PrPC (PRPC PROTEINS). The primary amino acid sequence of the two isoforms is identical. Human diseases caused by prions include CREUTZFELDT-JAKOB SYNDROME; GERSTMANN-STRAUSSLER SYNDROME; and INSOMNIA, FATAL FAMILIAL.
Canadian Medical Guide Definition Protein Hydrolysates
Canadian Medical Guide Definition Protein Isoforms - Different forms of a protein that may be produced from different genes, or from the same gene by alternative splicing.
Canadian Medical Guide Definition Protein Precursors
Canadian Medical Guide Definition Protein Subunits - Single chains of amino acids that are the units of multimeric PROTEINS. Multimeric proteins can be composed of identical or non-identical subunits. One or more monomeric subunits may compose a protomer which itself is a subunit structure of a larger assembly.
Canadian Medical Guide Definition Proteome - The protein complement of an organism coded for by its genome.
Canadian Medical Guide Definition Protozoan Proteins - Proteins found in any species of protozoan.
Canadian Medical Guide Definition Pulmonary Surfactant-Associated Proteins - Proteins found in the LUNG that act as PULMONARY SURFACTANTS.
Canadian Medical Guide Definition Receptors, Cytoplasmic and Nuclear - Proteins in the cytoplasm or nucleus that specifically bind signaling molecules and trigger changes which influence the behavior of cells. The major groups are the steroid hormone receptors (RECEPTORS, STEROID), which usually are found in the cytoplasm, and the thyroid hormone receptors (RECEPTORS, THYROID HORMONE), which usually are found in the nucleus. Receptors, unlike enzymes, generally do not catalyze chemical changes in their ligands.
Canadian Medical Guide Definition Receptors, Drug - Proteins that bind specific drugs with high affinity and trigger intracellular changes influencing the behavior of cells. Drug receptors are generally thought to be receptors for some endogenous substance not otherwise specified.
Canadian Medical Guide Definition Recombinant Proteins - Proteins prepared by recombinant DNA technology.
Canadian Medical Guide Definition Reptilian Proteins - Proteins obtained from species of REPTILES.
Canadian Medical Guide Definition Ribosomal Proteins - Proteins found in ribosomes. They are believed to have a catalytic function in reconstituting biologically active ribosomal subunits.
Canadian Medical Guide Definition Salivary Proteins - Proteins found in SALIVA and the SALIVARY GLANDS. Some show enzymatic activity, but their composition varies in different individuals.
Canadian Medical Guide Definition Scleroproteins - Simple proteins characterized by their insolubility and fibrous structure. Within the body, they perform a supportive or protective function.
Canadian Medical Guide Definition Seminal Plasma Proteins - Proteins found in SEMEN. Major seminal plasma proteins are secretory proteins from the male sex accessory glands, such as the SEMINAL VESICLES and the PROSTATE. They include the seminal vesicle-specific antigen, an ejaculate clotting protein; and the PROSTATE-SPECIFIC ANTIGEN, a protease and an esterase.
Canadian Medical Guide Definition Serpins - A family of serine proteinase inhibitors which are similar in amino acid sequence and mechanism of inhibition, but differ in their specificity toward proteolytic enzymes. This family includes alpha 1-antitrypsin, angiotensinogen, ovalbumin, antiplasmin, alpha 1-antichymotrypsin, thyroxine-binding protein, complement 1 inactivators, antithrombin III, heparin cofactor II, plasminogen inactivators, gene Y protein, placental plasminogen activator inhibitor, and barley Z protein. Some members of the serpin family may be substrates rather than inhibitors of SERINE ENDOPEPTIDASES, and some serpins occur in plants where their function is not known.
Canadian Medical Guide Definition Silver Proteins - Compounds of silver and proteins used as topical anti-infective agents.
Canadian Medical Guide Definition Thioredoxin - A hydrogen-carrying protein that participates in a variety of biochemical reactions including ribonucleotide reduction. Thioredoxin is oxidized from a dithiol to a disulfide during ribonucleotide reduction. The disulfide form is then reduced by NADPH in a reaction catalyzed by THIOREDOXIN REDUCTASE.
Canadian Medical Guide Definition Tissue Inhibitor of Metalloproteinases - A family of secreted proteins (TIMP-1; TIMP-2; and TIMP-3) that play a crucial role in regulating the activity of the secreted METALLOENDOPEPTIDASES (COLLAGENASES; stromelysins, GELATINASES). Of the three characterized, only TIMP-1 and TIMP-2 appear to have related primary structures and inhibitory properties. They influence the activation of the prometalloproteinase and act to modulate proteolysis of extracellular matrix, notably during tissue remodeling and inflammatory processes. On certain cell types, they can exhibit growth factor-like activity, and they can inhibit the tumorigenic and metastatic phenotype in cancer cells. (Pharmacol Ther 1993;59:329-41)
Canadian Medical Guide Definition Transcription Factors - Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.
Canadian Medical Guide Definition Ubiquitins - A family of proteins that are structurally-related to Ubiquitin. Ubiquitins and ubiquitin-like proteins participate in diverse cellular functions, such as protein degradation and HEAT-SHOCK RESPONSE, by conjugation to other proteins.
Canadian Medical Guide Definition Viral Proteins - Proteins found in any species of virus.

Proteins Medical Definitions and Terms

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