Carboxypeptidase B1, Tissue (CPB1)

Three different procarboxypeptidases A and two different procarboxypeptidases B have been isolated. The B1 and B2 forms differ from each other mainly in isoelectric point. Carboxypeptidase B1 is a highly tissue-specific protein and is a useful serum marker for acute pancreatitis and dysfunction of pancreatic transplants. It is not elevated in pancreatic carcinoma.

The deduced 416-amino acid preproenzyme (EC 3.4.17.2) has a 15-amino acid signal peptide and a 95-amino acid activation peptide. It shares 76% and 84% sequence identity with the rat and bovine homologs, respectively. DNA blot analysis indicated that the PCPB mRNA is transcribed from a single locus. Northern blot analysis demonstrated pancreas-specific expression.