title: Carboxypeptidase activity in the insulin secretory granule.
abstract: Carboxypeptidase activity was studied in subcellular fractions from a transplantable rat insulinoma and found to be localised principally in the insulin secretory granule. The activity, which was specific for peptide substrates with C-terminal basic amino acids, appeared to be a single enzyme with Mr 54000. This enzyme differed with respect to size and pH optimum from other basic amino acid-specific carboxypeptidases, such as carboxypeptidases B and N, and may be a secretory granule-specific enzyme involved in propolypeptide processing.
mesh_terms: D007516:Adenoma, Islet Cell / Q000201:enzymology*; D000818:Animals; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000378:metabolism*; D007340:Insulinoma / Q000201:enzymology*; D010190:Pancreatic Neoplasms / Q000201:enzymology*; D051381:Rats
chemical_list: D007328:Insulin; D002268:Carboxypeptidases