EVOLUTION OF NEUROPEPTIDE-Y AND ITS RELATED PEPTIDES

1. The neuropeptide Y (NPY) family of peptides includes also the gut e ndocrine peptide YY (PYY), tetrapod pancreatic polypeptide (PP), and f ish pancreatic peptide-tyrosine (PY). All peptides are 36 amino acids long. 2. Sequences from many types of vertebrates show that NPY has re mained extremely well conserved throughout vertebrate evolution with 9 2% identity between mammals and cartilaginous fishes. 3. PYY has 97-10 0% identity between cartilaginous fishes and bony fishes, but is less conserved in amphibians and mammals (83% identity between amphibians a nd sharks and 75% identity between mammals and sharks). 4. NPY and PYY share 70-80% identity in most species. 5. Both NPY and PYY were prese nt in the early vertebrate ancestor because both peptides have been fo und in lampreys. 6. The tissue distribution appears to have been large ly conserved between phyla, except that PW has more widespread neurona l expression in lower vertebrates. 7. Pancreatic polypeptide has diver ged considerably among tetrapods leaving only 50% identity between mam mals, birds/reptiles and frogs. 8. Several lines of evidence suggest t hat the PP gene arose by duplication of the PYY gene, probably in the early evolution of the tetrapods. 9. The pancreatic peptide PY found i n anglerfish and daddy sculpin may have resulted from an independent d uplication of the PYY gene. 10. The relationships of the recently desc ribed mollusc and worm peptides NPF and PYF with the NPY family still appear unclear.