Mapping of G protein coupling sites of the angiotensin II type 1 receptor.
Angiotensin II type 1 (AT1) receptors have been identified in a wide variety of tissues, including the kidney, liver, adrenal gland, cardiovascular system, and brain. AT1 receptors also mediate complex signaling mechanisms that elicit a diversity of specific physiological effects. The rat AT1A receptor has seven transmembrane domains and couples with three distinct G proteins: Gq, Gi, and Go. But it is unknown which domains of AT1A couple with and activate each type of G protein. To identify the domains responsible for the activation of various types of G protein, we studied the effect of five different synthetic peptides representing different domains of cytosolic segments of the rat AT1A receptor on the binding of the 35S-labeled stable analogue of GTP, GTP gamma S. Peptides P-3, which is located in the N-terminal region of the putative third intracellular loop of AT1A (residues 216 through 230), and P-5 (residues 306 through 320), corresponding to the N-terminal region of the C-terminal tail, were found to activate purified Gi1, Gi2, and Go proteins. These results indicate that not only the third cytosolic loop but also the C-terminal cytosolic domain of AT1A is important for Gi1, Gi2, and Go protein coupling and activation.
Shirai
H
H
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Takahashi
K
K
Katada
T
T
Inagami
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002874:Chromosome Mapping; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D011945:Receptors, Angiotensin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D010446:Peptide Fragments; D011945:Receptors, Angiotensin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins