Neuropeptide Y receptor gene y6: Multiple deaths or resurrections?

The neuropeptide Y family of G-protein-coupled receptors consists of five c loned members in mammals. Four genes give rise to functional receptors in a ll mammals investigated. The y6 gene is a pseudogene in human and pig and i s absent in rat, but generates a functional receptor in rabbit and mouse an d probably in the collared peccary (Pecari tajacu), a distant relative of t he pig family. We report here that the guinea pig y6 gene has a highly dist orted nucleotide sequence with multiple frame-shift mutations. One evolutio nary scenario may suggest that y6 was inactivated before the divergence of the mammalian orders and subsequently resurrected in some lineages. However , the pseudogene mutations seem to be distinct in human, pig, and guinea pi g, arguing for separate inactivation events. In either case, the y6 gene ha s a quite unusual evolutionary history with multiple independent deaths or resurrections. (C) 2000 Academic Press.