125I]Leu31, Pro34-PYY is a High Affinity Radioligand for Rat PP1/Y4 and Y1 Receptors: Evidence for Heterogeneity in Pancreatic Polypeptide Receptors

Abstract

Gehlert, D. R., D. A. Schober, S. L. Gackenheimer, L. Beavers, R. Gadski, I. Lundell and D. Larhammar. [125I]Leu31, Pro34-PYY is a high affinity radioligand for rat PP1/Y4 and Y1 receptors: Evidence for heterogeneity in pancreatic polypeptide receptors. Peptides 18(3) 397–401, 1997.—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 and Y6 receptors while PP has highest affinity for PP1. Pro34-substituted analogs of NPY and PYY have selectivity for Y1 and Y1-like receptors over Y2 receptors. In the present study, we found the putative Y1-selective radioligand, [125I]Leu31, Pro34-PYY, also binds with high affinity to the rat PP1 receptor in cell lines expressing the receptor. However, in rat brain sections, [125I]Leu31, Pro34-PYY does not appear to bind to the interpeduncular nucleus, a brain region containing a high density of [125I]-bPP binding sites. Therefore, it appears there is additional heterogeneity in receptors recognizing PP.