[5] PCSK1 and PCSK2 differentially cleave proopiomelanocortin and they act together to process proinsulin and proglucagon in pancreatic islets.

[6] PC1/3 is an enzyme that performs the proteolytic cleavage of prohormones to their intermediate (or sometimes completely cleaved) forms.

Proprotein convertase 1 is the enzyme largely responsible for the first step in the biosynthesis of insulin.

Following the action of proprotein convertase 1, a carboxypeptidase is required to remove the basic residues from the processing intermediate and generate the bioactive form of insulin.

There are nine subtilisin homologs in mammals; in addition to proprotein convertase 1 and 2, other members of this enzyme family include furin, PACE4, PC4, PC5/6, PC7/8, PCSK9, and SKI1/S1P.