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Peptide YY. Structure of the precursor and expression in exocrine pancreas
A B Leiter1, A Toder, H J Wolfe
1Division of Gastroenterology, New England Medical Center, Boston, Massachusetts 02111.
Insights
Researchers identified the precursor to Peptide YY (PYY), a gastrointestinal hormone, in rat pancreas. Its high expression suggests a local role in regulating pancreatic secretion.
Area of Science:
- Gastroenterology
- Molecular Biology
- Endocrinology
Background:
- Peptide YY (PYY) is a gastrointestinal hormone known to inhibit gastric and pancreatic secretions.
- The precise expression and function of PYY within the pancreas require further elucidation.
Purpose of the Study:
- To isolate and characterize the cDNA encoding the rat Peptide YY precursor.
- To investigate the expression patterns of the Peptide YY gene in rat tissues.
Main Methods:
- Screening of a rat intestinal lambda gt11 cDNA library using an antiserum against porcine PYY.
- Nucleotide sequencing of the isolated cDNA.
- RNA blot hybridization and in situ hybridization techniques.
Main Results:
- Isolation of a cDNA encoding a 98-residue rat PYY precursor, sharing sequence identity with porcine PYY.
- The precursor includes a signal sequence and a cleavage-amidation site.
- RNA blot and in situ hybridizations revealed significant PYY gene expression in the exocrine pancreas, localizing PYY cells exclusively there.
Conclusions:
- The rat PYY precursor structure is similar to related peptides like pancreatic polypeptide and neuropeptide Y.
- The high abundance of PYY in the pancreas suggests a paracrine role in regulating pancreatic enzyme secretion.
Abstract:
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.