| Type: | Family | Name: | Peptidase C1A |
| Description: | This group of cysteine peptidases belong to MEROPS peptidase family C1, sub-family C1A (papain family, clan CA). It includes proteins classed as non-peptidase homologues. These are have either been shown experimentally to lack peptidase activity or lack one or more of the active site residues. The papain family has a wide variety of activities, including broad-range (papain) and narrow-range endo-peptidases, aminopeptidases, dipeptidyl peptidases and enzymes with both exo- and endo-peptidase activity []. Members of the papain family are widespread, found in baculovirus [], eubacteria, yeast, and practically all protozoa, plants and mammals []. The proteins are typicallylysosomal or secreted, and proteolytic cleavage of the propeptide is required for enzyme activation, although bleomycin hydrolase is cytosolic in fungi and mammals []. Papain-like cysteine proteinases are essentially synthesised as inactive proenzymes (zymogens) with N-terminal propeptide regions. The activation process of these enzymes includes the removal ofpropeptide regions. The propeptide regions serve a variety of functions in vivo and in vitro. The pro-region is required for the proper folding of the newly synthesised enzyme, the inactivation of the peptidase domain and stabilisation of the enzyme against denaturing at neutral to alkaline pH conditions. Amino acid residues within the pro-region mediate their membrane association, and play a role in the transport of the proenzyme to lysosomes. Among the most notable features of propeptides is their ability to inhibit the activity of their cognate enzymes and that certain propeptides exhibit high selectivity for inhibition of the peptidases from which they originate []. | Short Name: | Peptidase_C1A |
