Members of the subtilisin-like proprotein convertase family process latent precursor proteins into their biologically active products. The protein encoded by this gene appears to function as an endogenous inhibitor of proprotein convertase subtilisin/kexin type 1. [provided by RefSeq, Jul 2008].
Function: May function in the control of the neuroendocrine secretory pathway. Proposed be a specific endogenous inhibitor of PCSK1. ProSAAS and Big PEN-LEN, both containing the C-terminal inhibitory domain, but not the further processed peptides reduce PCSK1 activity in the endoplasmic reticulum and Golgi. It reduces the activity of the 84 kDa form but not the autocatalytically derived 66 kDa form of PCSK1. Subsequent processing of proSAAS may eliminate the inhibition. Slows down convertase-mediated processing of proopiomelanocortin and proenkephalin. May control the intracellular timing of PCSK1 rather than its total level of activity. The function of the processed secreted peptides is not known (By similarity).