A family of subtilisin-like peptidases, of which furin is another example. All members are from eukaryotes although there are various kexin-like peptidases from prokaryotes. Kexin itself is a yeast serine peptidase of the S8 family (EC 18.104.22.168) that processes the precursors of α-factors and killer toxin; the mammalian kexin-like peptidases are involved in processing of various proproteins. Proprotein convertase-1 (PC1; proprotein convertase subtilisin/kexin-type 1, PCSK1; EC 22.214.171.124, 753 aa) and PC2 (EC 126.96.36.199, 638 aa) are neuroendocrine convertases that differentially cleave pro-opiomelanocortin and process proinsulin and proglucagon in pancreatic islets. PC4 (proprotein convertase subtilisin/kexin-type 4, PCSK4, 755 aa) is involved in processing pro-IGF2 (pro-*insulin-like growth factor II) to produce the intermediate IGF2 (1–102) that is further cleaved to the active form by another peptidase. Mutation in PCSK4 is associated with intrauterine growth restriction. PC5 (PCSK5, 913 aa) mediates post-translational endoproteolytic processing of several integrin α subunits. The gene encoding the proprotein convertase subtilisin/kexin type 9 (PCSK9, 692 aa) is linked to familial hypercholesterolemia and the product is involved in hepatocyte-specific low-density lipoprotein receptor degradation.
Subjects: Medicine and Health.