Peptide YY. Structure of the precursor and expression in exocrine pancreas.

Peptide YY is a 36-residue gastrointestinal hormone which inhibits both pancreatic and gastric secretion. We have isolated a cDNA encoding the peptide YY precursor by screening a rat intestinal lambda gt11 cDNA library with an antiserum directed against the porcine hormone. The nucleotide sequence of the cDNA encodes a 98-residue protein (molecular weight, 11, 121) which has an amino acid sequence identical to that of porcine peptide YY. Rat peptide YY is preceded immediately by a signal sequence and followed by a cleavage-amidation sequence Gly-Lys-Arg plus 31 additional amino acids. Thus the peptide YY precursor is similar in structure to that of two related peptides, pancreatic polypeptide and neuropeptide Y. RNA blot hybridizations reveal that the peptide YY gene is much more actively expressed in pancreas than previously realized. In situ hybridizations localized peptide YY cells exclusively to the exocrine pancreas. The abundance of peptide YY in one of its target organs, the pancreas, suggests a paracrine mechanism for peptide YY in regulating pancreatic enzyme secretion.