catalytic activity:Hydrolysis of proteins with broad specificity for peptide bonds. Preferentially cleaves -Arg-Arg-|-Xaa bonds in small molecule substrates (thus differing from cathepsin L). In addition to being an endopeptidase, shows peptidyl-dipeptidase activity, liberating C-terminal dipeptides.,function:Thiol protease which is believed to participate in intracellular degradation and turnover of proteins. Has also been implicated in tumor invasion and metastasis.,similarity:Belongs to the peptidase C1 family.,subcellular location:Identified by mass spectrometry in melanosome fractions from stage I to stage IV.,subunit:Dimer of a heavy chain and a light chain cross-linked by a disulfide bond.,
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Function:
proteolysis, response to wounding, regulation of cell death, regulation of apoptosis, regulation of programmed cell death,
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Cellular Localization:
Lysosome . Melanosome . Secreted, extracellular space . Apical cell membrane ; Peripheral membrane protein ; Extracellular side . Identified by mass spectrometry in melanosome fractions from stage I to stage IV (PubMed:17081065). Localizes to the lumen of thyroid follicles and to the apical membrane of thyroid epithelial cells (By similarity). .
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Tissue Expression:
Expressed in the stratum spinosum of the epidermis. Weak expression is detected in the stratum granulosum.