Identification of regions in the human angiotensin II receptor type 1 responsible for Gi and Gq coupling by mutagenesis study.
Previous mutagenesis studies of angiotensin II (Ang II) receptor type 1 (AT1) have focused on determining the regions responsible for Gq coupling using the rat AT1 receptor. We created human AT1 receptor mutants, expressed them in COS-7 cells, and identified the domains crucial for Gi coupling as well as for Gq coupling. Substitution of Asp125, Arg126, Tyr127, and Met134 by Gly, Gly, Ala, and Ala in the highly conserved sequence of the second intracellular loop in most G protein-coupled receptors provided a mutant AT1 receptor which lost the ability to couple to both Gq and Gi with no impairment in its binding to Ang II. A truncated mutant lacking the carboxyl terminal 50 residues was completely deficient in coupling to Gi, whereas it retained full ability to bind to Gq, in contrast to the rat AT1 receptor. These findings demonstrate that the cytoplasmic tail in the human AT1 receptor is the determinant of specific Gi coupling.
Shibata
T
T
Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
Suzuki
C
C
Ohnishi
J
J
Murakami
K
K
Miyazaki
H
H
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010716:Phosphatidylinositols / Q000378:metabolism; D017354:Point Mutation; D051381:Rats; D011945:Receptors, Angiotensin / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000067956:Adenylyl Cyclase Inhibitors; D010716:Phosphatidylinositols; D011945:Receptors, Angiotensin; D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella; D000804:Angiotensin II; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine