A role for K268 in V2R folding.
The V2 vasopressin receptor, a member of the rhodopsin subfamily of GPCRs, mediates arginine vasopressin control of water reabsorption in the kidney by activating Gs. Requirement of the third intracellular loop of the V2R for G(s) activation was identified by introducing V2R segments into the Gq coupled V1aR [Liu, J. and Wess, J. (1996) J. Biol. Chem. 271, 8772-8778]; the same approach recognized glutamate 231 and glutamine 225 at the amino terminus of loop 3i as being needed for signal transduction. Site-directed mutagenesis of the V2R confirmed their observations. Recently, we found that a positively charged amino acid at codon 268 is essential for V2R expression, although a double-mutant bearing lysine at position 231 and glutamic acid at position 268 was expressed at higher levels than the wild type V2R and displayed unchanged ligand-binding affinity. Ligand-induced internalization and phosphorylation of the double-mutant receptor was indistinguishable from that observed with the wild type protein but signaling activity was greatly diminished. The data suggested these two amino acids might interact with each other and might play a role in promoting GDP/GTP exchange.
Gouill
Christian Le
CL
Department of Anesthesiology, UCLA School of Medicine, Los Angeles, CA 90095, USA.
Darden
Thomas
T
Madziva
Michael T
MT
Birnbaumer
Mariel
M
D000595:Amino Acid Sequence; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017510:Protein Folding; D017483:Receptors, Vasopressin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction
D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D008239:Lysine