Description
Thiol protease important for the overall degradation of proteins in lysosomes (Probable). Involved in the solubilization of cross-linked TG/thyroglobulin and in the subsequent release of thyroid hormone thyroxine (T4) by limited proteolysis of TG/thyroglobulin in the thyroid follicle lumen (PubMed: 12782676). In neuroendocrine chromaffin cells secretory vesicles, catalyzes the prohormone proenkephalin processing to the active enkephalin peptide neurotransmitter (PubMed: 12869695). In thymus, regulates CD4(+) T cell positive selection by generating the major histocompatibility complex class II (MHCII) bound peptide ligands presented by cortical thymic epithelial cells (PubMed: 12021314). Also mediates invariant chain processing in cortical thymic epithelial cells (PubMed: 9545226). Major elastin-degrading enzyme at neutral pH. Accumulates as a mature and active enzyme in the extracellular space of antigen presenting cells (APCs) to regulate degradation of the extracellular matrix in the course of inflammation (PubMed: 12417635). Secreted form generates endostatin from COL18A1 (PubMed: 10716919). Critical for cardiac morphology and function (PubMed: 11972068). Plays an important role in hair follicle morphogenesis and cycling, as well as epidermal differentiation (PubMed: 12163394). Required for maximal stimulation of steroidogenesis by TIMP1 (By similarity)