[I-125] LEU(31), PRO(34)-PYY IS A HIGH-AFFINITY RADIOLIGAND FOR RAT PP1 Y4 AND Y1 RECEPTORS - EVIDENCE FOR HETEROGENEITY IN PANCREATIC-POLYPEPTIDE RECEPTORS/

Cloned receptors for the PP-fold peptides are subdivided into Y1, Y2, PP1/Y4, Y5 and Y6. NPY and PYY have similar affinity for Y1, Y2, Y5 an d Y6 receptors while PP has highest affinity for PP1. Pro(34)-substitu ted analogs of NPY and PYY have selectivity for Y1 and Y1-like recepto rs over Y2 receptors. In the present study, we found the putative Y1-s elective radioligand, [I-125]Leu(31), Pro(34)-PYY, also binds with hig h affinity to the rat PP1 receptor in cell lines expressing the recept or. However, in rat brain sections, [I-125]Leu(31), Pro(34)-PYY does n ot appear to bind to the interpeduncular nucleus, a brain region conta ining a high density of [I-125]-bPP binding sites. Therefore, it appea rs there is additional heterogeneity in receptors recognizing PP. (C) 1997 Elsevier Science Inc.