Truncation of the receptor carboxyl terminus impairs membrane signaling but not ligand binding of human ETB endothelin receptor.
Human ETB endothelin receptor (hETBR) is a heptahelical G-protein-coupled receptor consisting of 442 amino acids whose carboxyl (C)-intracellular region has four and twelve sites for potential palmitoylation and phosphorylation, respectively. In order to elucidate the functional roles of these modification sites, we constructed a series of C-terminal truncated hETBRs and expressed them in Ltk- cells. All the truncated hETBRs showed ligand-binding profiles similar to those of the wild-type hETBR. The truncated receptors holding Cys-402 retained both normal intracellular calcium ([Ca2+]i) response and its rapid desensitization; however, the deleted receptors lacking Cys-402 failed to induce the [Ca2+]i response. These results showed that Cys-402 of hETBR is necessary for its intracellular calcium signaling and that at least ten of twelve putative phosphorylation sites are irresponsible for the agonist-induced desensitization.
Department of Molecular and Cellular Pharmacology, National Children's Medical Research Center, Tokyo, Japan.
T
T
Koshimizu
G
G
Tsujimoto
K
K
Ono
T
T
Masaki
A
A
Sakamoto
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D016232:Endothelins / Q000494:pharmacology; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D010169:Palmitic Acids / Q000378:metabolism; D010766:Phosphorylation; D017466:Receptors, Endothelin / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D017384:Sequence Deletion; D015398:Signal Transduction; D014162:Transfection
D017931:DNA Primers; D018076:DNA, Complementary; D016232:Endothelins; D008024:Ligands; D010169:Palmitic Acids; D017466:Receptors, Endothelin; D002118:Calcium