This region of 270 amino acids is the seven transmembrane alpha-helical domains included within five GPCRRHODOPSN4 motifs of a G-protein-coupled-receptor (GPCR) protein, conserved from nematodes to humans. GPCRs are integral membrane receptors whose intracellular actions are mediated by signalling pathways involving G proteins and downstream secondary messengers [1].

1: Inhibition of experimental intimal thickening in mice lacking a novel G-protein-coupled receptor. Tsukada S, Iwai M, Nishiu J, Itoh M, Tomoike H, Horiuchi M, Nakamura Y, Tanaka T; Circulation. 2003;107:313-319. PMID:12538434