| protein folding | A rapid biochemical reaction involved in the formation of proteins. It begins even before a protein has been completely synthesised and proceeds through discrete intermediates (primary, secondary, and tertiary structures) before the final structure (quaternary structure) is developed. (12 Dec 1998) |
|---|---|
| protein G | Protein from Group C Streptococci that binds the Fc portion of IgG. Is less species specific than Protein A. (18 Nov 1997) |
| protein geranylgeranyltransferase | <enzyme> Involved in protein isoprenylation; transfers geranylgeranyl group to cys fourth from the c-terminal of GTP-binding proteins; amino acid sequence of beta subunit of ggtase-i known; genbank l24116; see also rab, ras, and rhoa p21 geranylgeranyl- transferases and component a, rab geranylgeranyltransferase Registry number: EC 2.5.1.- Synonym: protein ggtase, geranylgeranyltransferase type-i, ggtase-i, geranylgeranyl-protein transferase type 1 (26 Jun 1999) |
| protein-glutamine gamma-glutamyltransferase | <enzyme> An enzyme that catalyses the reaction of protein glutamine and an alkylamine to yield protein n(5)-alkylglutamine and ammonia. The gamma-carboxamide groups of peptide-bound glutamine residues act as acyl donors, and the 6-amino groups of protein- and peptide-bound lysine residues act as acceptors, to give intra- and inter-molecular n(6)-(5-glutamyl)lysine crosslinks. In the epidermis these cross-linked proteins are involved in the formation of the cornified envelope of the stratum corneum cells. In the plasma, the transglutaminase is called factor xiiia, the activated form of factor xiii. The crosslinking results in the stabilization of the fibrin clot. Pharmacological action: coagulants. Chemical name: Protein-glutamine:amine gamma-glutamyltransferase Registry number: EC 2.3.2.13 (12 Dec 1998) |
| protein-histidine kinase | <enzyme> Sass involved in transduction of starvation and cell density inputs; hkna isolated from bacillus thuringiensis; ciah isolated from streptococcus pneumoniae; do not confuse with plp1 protein Registry number: EC 2.7.3.- Synonym: histidine protein kinase, histidine kinase, hkna gene product, ciah gene product, kinc gene product, prrb gene product, plec gene product, mxcq gene product, rese gene product, hpka gene product, comd gene product, plpa gene product (phytochrome-like), divj gene product, sensor histidine kinase, sass gene product (26 Jun 1999) |
| protein hybridization | The formation of a protein consisting of two or more polypeptide chains from separate and different polypeptide chains. (12 Dec 1998) |
| protein hydrolysate | A sterile solution of amino acids and soft chain peptides prepared from a suitable protein by acid or enzymatic hydrolysis; used intravenously for the maintenance of positive nitrogen balance in severe illness, and after surgery involving the alimentary tract; or used orally in the diets of infants allergic to milk or as a supplement when high protein intake from ordinary foods cannot be accomplished. (05 Mar 2000) |
| protein isoprenylation | A post-translational modification of proteins by the attachment of an isoprenoid to the c-terminal cysteine residue. The isoprenoids used, farnesyl diphosphate or geranylgeranyl diphosphate, are derived from the same biochemical pathway that produces cholesterol. (12 Dec 1998) |
| protein kinase | <enzyme> Enzyme catalysing transfer of phosphate from ATP to hydroxyl side chains on proteins, causing changes in function. most phosphate on proteins of animal cells is on serine residues, less on threonine, with a very small amount on tyrosine residues. Tyrosine kinases phosphorylate proteins on tyrosine, serine / threonine kinases on serine or threonine. (18 Nov 1997) |
| protein kinase B kinase | <enzyme> Phosphorylates and activates protein kinase b on threonine-308; requires phosphatidylinositol-3,4,5-trisphosphate Registry number: EC 2.7.10.- Synonym: upstream kinase, pkb kinase (26 Jun 1999) |
| protein kinase c | <enzyme> An enzyme that phosphorylates proteins on serine or threonine residues in the presence of physiological concentrations of calcium and membrane phospholipids. The additional presence of diacylglycerols markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by phorbol esters and it is believed that protein kinase c is the receptor protein of tumour-promoting phorbol esters. Registry number: EC 2.7.1.- (12 Dec 1998) |
| protein-losing enteropathies | A series of gastrointestinal disorders which share in common the excessive loss of protein, mainly albumin, across the gut wall. They occur in the stomach (menetrier disease), as well as the small bowel (intestinal lymphangiectases, assorted inflammatory states). They are also occasionally associated with congestive heart failure (again a small bowel protein loss). (12 Dec 1998) |
| protein-losing enteropathy | Condition in which plasma protein is lost to excess into the intestine. This can be due to diverse causes including gluten enteropathy, extensive ulceration of the intestine, intestinal lymphatic blockage, and infiltration of leukaemic cells into the intestinal wall. (12 Dec 1998) |
| protein-lysine 6-oxidase | <enzyme> An enzyme oxidizing peptidyl-lysyl-peptide in the presence of water & molecular oxygen to yield peptidyl-allysyl-peptide plus ammonia & hydrogen peroxide. Chemical name: Protein-L-lysine:oxygen 6-oxidoreductase (deaminating) Registry number: EC 1.4.3.13 (12 Dec 1998) |
| protein malnutrition | Children are particularly prone to develop protein malnutrition. To grow, children have to consume enough nitrogen-containing food (protein) to maintain a positive nitrogen balance whereas adults need only be in nitrogen equilibrium. (12 Dec 1998) |