Relaxin/Insulin Like Family Peptide Receptor 4 (RXFP4)

GPR100 is a member of the rhodopsin family of G protein-coupled receptors (GPRs) .By searching databases for sequences similar to rhodopsin-like GPRs, Fredriksson et al. (2003) identified GPR100. The deduced 374-amino acid protein assumes a classic 7-transmembrane (TM) topology and contains an NSxxNPxxY motif in TM7. In place of the DRY motif in the intracellular side of TM3, GPR100 contains an ARY motif. GPR100 shares 78% amino acid identity with mouse Gpr100. The TM domains of mouse and human GPR100 are nearly 100% conserved, with most differences in the N and C termini. EST database analysis indicated that GPR100 is expressed in bone marrow. N-terminus and EL2 domains of RXFP3 and RXFP4 are involved in ligand binding while TM2, 3, and 5 are critical for receptor activation.