Catalytic activity:Processes precursors containing basic and hydrophobic/aliphatic residues at P4 and P2, respectively, with a relatively relaxed acceptance of amino acids at P1 and P3.,cofactor:Calcium.,enzyme regulation:Inhibited by divalent copper and zinc ions, but not by nickel or cobalt. Inhibited by its prosegment, but not smaller fragments thereof.,Function:Catalyzes the first step in the proteolytic activation of the sterol regulatory element-binding proteins (SREBPs). Other known substrates are BDNF and ATF6. Cleaves after hydrophobic or small residues, provided that Arg or Lys is in position P4. Cleaves known substrates after Arg-Ser-Val-Leu (SERBP-2), Arg-His-Leu-Leu (ATF6), Arg-Gly-Leu-Thr (BDNF) and its own propeptide after Arg-Arg-Leu-Leu.,induction:Down-regulated by sterols.,PTM:The 148 kDa zymogen is processed progressively into two membrane-bound 120 and 106 kDa forms in the endoplasmic reticulum, and late into a secreted 98 kDa form. The propeptide is autocatalytically removed through an intramolecular cleavage after Leu-186. Further cleavage generates 14, 10, and 8kDa intermediates.,similarity:Belongs to the peptidase S8 family.,subcellular location:May sort to other organelles, including lysosomal and/or endosomal compartments.,tissue specificity:Widely expressed.,
show all