Canine Pancreatic Polypeptide Complementary Deoxyribonucleic Acid Sequence: Pancreatic Polypeptide and Insulin Messenger Ribonucleic Acid Distribution in the Lobes of the Pancreas

The structure of the canine prepropancreatic polypeptide (preproPP) cDNA was determined. The nucleotide sequence conservation between human and canine preproPP is very high for the signal peptide (82%) and the region coding for the 36 amino acid pancreatic polypeptide (PP) (92%). The overall sequence homology for the C-terminal portion of proPP containing the icosapeptide and a C-terminal extension peptide is only 63% whereas the 3'-untranslated regions of human and canine PP mRNA share 73% homology after alignment for maximal homology. The only sequence conservation in icosapeptide is the region coding for the last 10 amino acids of the icosapeptide. Comparison of PP immunoactivity and PP mRNA concentrations in extracts of the developmentally distinct uncinate process and splenic lobes of the canine pancreas revealed the same ratio of mRNA concentrations (16 +/- 6.5) and PP peptide concentrations (18 +/- 7.0) in the uncinate process compared to the splenic lobe (n = 6). However, a similar comparison of insulin C-peptide (CP) immunoactivity and insulin mRNA concentration revealed a smaller ratio of CP immunoactivity (0.37 +/- 0.05) than insulin mRNA (0.58 +/- 0.10) between the same lobes (P less than 0.0074, n = 6). This increased steady state CP concentration relative to insulin mRNA in splenic lobe compared to the uncinate process was not observed for PP peptide and mRNA.