title: The place of human gamma-trace (cystatin C) amongst the cysteine proteinase inhibitors.
abstract: Native gamma-trace, a small basic protein present in high concentration in cerebrospinal fluid, semen and neuroendocrine cells, but of unknown biological function, is shown to be a potent inhibitor of the cysteine proteinases papain, ficin, and human cathepsins B, H and L. It proves to be the tightest -binding protein inhibitor of cathepsin B so far discovered. The name cystatin C is proposed for gamma-trace to reflect the many similarities in activity and structure to chicken egg-white cystatin and mammalian cystatins A and B. The inhibition constants of cystatin C, taken together with its widespread distribution in human tissues and extracellular fluids, suggest that a physiological function could well be the regulation of cysteine proteinase activity.
mesh_terms: D002403:Cathepsins / Q000037:antagonists & inhibitors; D055316:Cystatin C; D015891:Cystatins; D004355:Drug Stability; D000939:Epitopes / Q000276:immunology; D005361:Ficain / Q000037:antagonists & inhibitors; D006801:Humans; D007700:Kinetics; D010206:Papain / Q000037:antagonists & inhibitors; D011480:Protease Inhibitors; D011506:Proteins / Q000276:immunology / Q000494:pharmacology*
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D000939:Epitopes; D011480:Protease Inhibitors; D011506:Proteins; D002403:Cathepsins; D010206:Papain; D005361:Ficain