title: Role of the conserved DRY motif on G protein activation of rat angiotensin II receptor type 1A.
abstract: To delineate the functional importance of the highly conserved triplet amino acid sequence, Asp-Arg-Tyr (DRY) among G protein-coupled receptors in the second intracellular loop, these residues of rat angiotensin II (Ang II) receptor type 1A (AT(1A)) were changed by alanine or glycine by site-directed mutagenesis. These mutant receptors were stably expressed in CHO-K1 cells, and the binding of Ang II, GTP effect, InsP(3) production, and the acidification of the medium in response to Ang II were determined. The effects of GTPgammaS on Ang II binding in the mutant receptors D125A and D125G were markedly reduced. InsP(3) production of the mutant D125A, D125G, R126A, and R126G was markedly reduced. Extracellular acidification of D125A was not distinguishable from untransfected CHO-K1 cells. Mutant Y127A was able to produce InsP(3) and acidify medium comparable with wild type AT(1A). These results indicate as follows; Asp(125) is essential for intracellular signal transduction involving G protein coupling, Arg(126) is essential for coupling of G(q) protein but not other G proteins, and Tyr(127) is not important for G protein coupling.
authors.affiliation: Department of Clinical Nursing and Pediatrics, Yamanashi Medical University, Nakakoma-gun, Yamanashi 409-3898, Japan. kohyama@res.yamanashi-med.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Ohyama
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yamano
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Sano
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Nakagomi
authors.forename: Manabu
authors.initials: M
authors.lastname: Wada
authors.forename: Tadashi
authors.initials: T
authors.lastname: Inagami
mesh_terms: D020816:Amino Acid Motifs; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D017124:Conserved Sequence; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D051381:Rats; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D015544:Inositol 1,4,5-Trisphosphate; D020962:Heterotrimeric GTP-Binding Proteins