Marapsin (MPN)

Pancreasin is a pancreatic tryptic serine peptidase that cleaves peptides after an arginine residue. The deduced 290-amino acid preproprotease contains an N-terminal signal peptide, followed by a prosequence and a 256-amino acid serine protease catalytic domain. The catalytic domain contains the essential catalytic triad (his75, asp124, and ser229) conserved in serine proteases, as well as 2 putative N-glycosylation sites. Northern blot analysis revealed expression of pancreasin only in pancreas. RT-PCR detected expression in several other tissues, including strong expression in lung and placenta. Immunocytochemical analysis of pancreatic carcinoma cells revealed cytoplasmic reactivity, and transfected Chinese hamster ovary cells secreted pancreasin into the medium.