Origins of the many NPY-family receptors in mammals

The NPY system has a multitude of effects and is particularly well known fo r its role in appetite regulation. We have found that the five presently kn own receptors in mammals arose very early in vertebrate evolution before th e appearance of jawed vertebrates 400 million years ago. The genes Y-1, Y-2 and Y-5 arose by local duplications and are still present on the same chro mosome in human and pig. Duplications of this chromosome led to the Y-1-lik e genes Y-4 and y(6). We find evidence for two occasions where receptor sub types probably arose before peptide genes were duplicated. These observatio ns pertain to the discussion whether ligands or receptors tend to appear fi rst in evolution. The roles of Y-1 and Y-5 in feeding may differ between sp ecies demonstrating the importance of performing functional studies in addi tional mammals to mouse and rat. (C) 2001 Published by Elsevier Science Inc .