Binding properties of three neuropeptide Y receptor subtypes from zebrafish: Comparison with mammalian Y1 receptors

Neuropeptide Y (NPY) and peptide YY (PYY) are two related 36-amino-acid pep tides found in all vertebrates and are involved in many physiological proce sses. Five receptor subtypes have been cloned in mammals (YI, Y2, Y4, Y5, a nd y6). We have recently cloned three NPY/PYY receptor subtypes in zebrafis h, called Ya, Yb, and Yc. Here we report on a direct comparison of the phar macological properties of these three receptors in vitro using porcine NPY with alanine substitutions in positions 33-36 as ligands and three analogue s with internal deletions: [Ahx(8-20)]NPY, [Ahx(8-20), Pro(34)]NPY, and [Ah X(5-24)]NPY. In all cases, the zYc receptor was the most sensitive to the m odifications of the NPY molecule and zYa was the least sensitive (except fo r the Arg --> Ala replacement at position 33). Our data identified zYa as a receptor that can bind ligands specific for Y1, Y2, and Y4 receptors, whil e zYb and zYc were more Y1-like. All peptides with internal deletions bound to the zYa receptor with affinities similar to that of intact pNPY. Neithe r the YI-selective antagonists BIBP3226 and SR120819A nor the Y2-selective BIIE0246 bound to any of the zebrafish receptors, although the amino acids identified as important for BIBP3226 binding were almost completely conserv ed. These results may prove helpful in molecular modeling of the three-dime nsional receptor structure. BIOCHEM PHARMACOL 60;12: 1815-1822, 2000. (C) 2 000 Elsevier Science Inc.