DISTRIBUTION OF THE KEXIN FAMILY PROTEASES IN PANCREATIC-ISLETS - PACE4C IS SPECIFICALLY EXPRESSED IN B-CELLS OF PANCREATIC-ISLETS

The distribution of Kexin family proteases in adult rat pancreatic isl ets was investigated by immunohistochemical means using a series of sp ecific antibodies specific for PC1, PC2, PC6, Furin, PACE4A and a rece ntly identified member of the Kexin family, PACE4C. PACE4C expression was limited to B cells of the pancreatic islets. PC2 was found in A an d in some D cells more than in B cells and PC1 was evident only in B c ells. Furin and PC6 were weakly and evenly expressed in the entire isl et. PACE4A was hardly found in the islets. These findings indicated th at individual Kexin family proteases are uniquely distributed in the i slets and suggested that these proteases share roles in these cells as follows: PC2 Is involved in the peptide hormone precursor processing in A cells and in D cells, and PACE4C, PC1 and PC2 (mainly PACE4C and PC1) are responsible for the processing event(s) specific to B cells.