ESTs for Xenotropic And Polytropic Retrovirus Receptor (XPR1) have been isolated from brain, breast, kidney, pancreas, placenta, prostate, skeletal muscle, testis, and tonsil libraries. G-protein Coupled Receptors (GPCRs) comprise one of the largest families of signaling molecules with more thana thousandmembers currently predicted to exist. All GPCRs share a structural motif consisting of seven membrane-spanning helices, and exist in both active and inactive forms. An array of activating ligands participate in the conformation of GPCRs which leads to signaling via G-proteins and downstream effectors. Ongoing studies have also shown the vast series of reactions which participate in the negative regulation of GPCRs. This "turn-off" activity has tremendous implications for the physiological action of the cell, and continues to drive pharmacological research for new drug candidates. Twoblockbuster drugs which have been developed as GPCR-targetedpharmaceuticals are Zyprexa (Eli Lilly) and Claritin (Schering-Plough) which have multi-billion dollar shares of the mental health and allergy markets, respectively.
Protein SYG1 homolog; SYG1; X-receptor; X3; Xenotropic and polytropic murine leukemia virus receptor X3; Xenotropic and polytropic retrovirus receptor 1