|SMART accession number:||SM00043|
|Description:||Cystatins are a family of cysteine protease inhibitors that occur mainly as single domain proteins. However some extracellular proteins such as kininogen, His-rich glycoprotein and fetuin also contain these domains.|
|Interpro abstract (IPR000010):|
The cystatins are cysteine proteinase inhibitors belonging to MEROPS inhibitor family I25, clan IH [(PUBMED:2107324), (PUBMED:14587292), (PUBMED:1855589)]. They mainly inhibit peptidases belonging to peptidase families C1 (papain family) and C13 (legumain family). The cystatin family includes:
All true cystatins inhibit cysteine peptidases of the papain family (MEROPS peptidase family C1), and some also inhibit legumain family enzymes (MEROPS peptidase family C13). These peptidases play key roles in physiological processes, such as intracellular protein degradation (cathepsins B, H and L), are pivotal in the remodelling of bone (cathepsin K), and may be important in the control of antigen presentation (cathepsin S, mammalian legumain). Moreover, the activities of such peptidases are increased in pathophysiological conditions, such as cancer metastasis and inflammation. Additionally, such peptidases are essential for several pathogenic parasites and bacteria. Thus in animals cystatins not only have capacity to regulate normal body processes and perhaps cause disease when down-regulated, but in other organisms may also participate in defence against biotic and abiotic stress.
|GO function:||cysteine-type endopeptidase inhibitor activity (GO:0004869)|
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