EVOLUTION OF THE EVOLUTION NEUROPEPTIDE Y-PEPTIDE YY FAMILY

Neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP) form a family of 36-amino-acid peptides. DNA clones for NPY and PYY f rom several vertebrate species, including the river lamprey, show that both peptide genes were already present in the early vertebrate ances tor and that they have remained highly conserved during evolution. The PP gene probably arose as a copy of the PYY gene in early tetrapods. In situ hybridization shows that PW expression is more widespread in t he brain of lamprey than of mammals. We have cloned the zebrafish PYY (and NPY) gene to investigate whether this is a common feature among v ertebrates. Clones have also been isolated for several NPY/PYY recepto rs in rat, human, and zebrafish to unravel the evolution of the recept or gene family. The results suggest that there may be at least four di stinct receptor genes in bony fish and mammals.