Structural variation of G protein-coupled receptor in birds

Abstract

G protein-coupled receptors (GPCRs) are key regulators of various vital biological processes. Regardless of their physiological significance, GPCRs generally harbor a certain number of amino acid substitutions, as well as insertions/deletions, particularly in the loop and tail regions, even at the species level. We previously revealed that the C-terminal domain of avian GPCRs shows length variations at the intra-species level. The presence or absence of deletion in helix 8 of the arginine vasotocin receptor affected the pattern of putative palmitoylation sites in the zebra finch. Moreover, Turdus thrushes harbored 18-amino acid tandem duplications at the distal part of the C-terminal tails of the mesotocin receptor. These findings illustrated that avian neuropeptide receptors accommodate structural changes at the C-terminal tails as a source of genetic variation that may lead to phenotypic differences in natural populations as a consequence of natural selection.