G protein-coupled receptors (GPCR) are used ubiquitously and widely for signal
transduction across the plasma membrane. The ligands for GPCRs are structurally diverse
and include peptides, odorants, photon, ions and lipids. It is thought that GPCRs evolved by
gene duplication and mutational events that diversified the ligand binding and signaling
properties, thereby resulting in paralogues in various organisms. Genomic sequencing
efforts of various organisms indicate that GPCRs evolved very early in evolution; for …