THE NEUROPEPTIDE YY1 RECEPTOR-SELECTIVE RADIOLIGAND, [I-125] [LEU(31),PRO(34)]PEPTIDE YY, IS ALSO A HIGH-AFFINITY RADIOLIGAND FOR HUMAN PANCREATIC-POLYPEPTIDE-1 RECEPTORS

A number of receptors for the pancreatic polypeptide-fold peptides are proposed based on findings from pharmacology and molecular biology st udies. Neuropeptide Y and peptide YY have similar affinity for neurope ptide Y Y-1 and neuropeptide Y Y-2 while pancreatic polypeptide has hi ghest affinity for pancreatic polypeptide 1. Pro(34)-substituted analo gs of neuropeptide Y and peptide YY have selectivity for neuropeptide Y Y-1 over neuropeptide Y Y-2 receptors. In the present study, we foun d that one such 'neuropeptide Y Y-1-selective' radioligand, [I-125][Le u(31),pro(34)]peptide YY, also binds with high affinity to the pancrea tic polypeptide 1 receptor. Therefore, caution needs to be exercised w hen using Pro(34)-analogs to define the neuropeptide Y Y-1 receptor in vivo and using tissue preparations.