title: G-Protein binding domains of the angiotensin II AT1A receptors mapped with synthetic peptides selected from the receptor sequence.
abstract: The vascular angiotensin II type 1 receptor (AT1AR) is a member of the G-protein-coupled receptor superfamily. We mapped the G-protein binding domains of the AT1AR using synthetic peptides selected from the receptor sequence, which interfere with AT1AR-G-protein coupling. Membrane GTPase activity was used as a measure of the functional coupling in rat vascular smooth muscle cells. Peptides corresponding to the N-terminal region of the second intracellular loop (residues 125-137), the N-terminal region of the third intracellular loop (217-227) and the juxtamembranous region of the C-terminal tail (304-316) inhibited angiotensin II-induced GTPase activation by 30%, 30%, and 70%, respectively. The latter two domains (217-227 and 304-316) are predicted to form amphiphilic alpha-helices. Only the peptide representing residues 217-227 stimulated basal activity (45%). No synthetic peptide had a significant effect on either the number or the affinity of the AT1AR binding. These observations indicate that domains of the second and third regions and the cytoplasmic tail of the AT1AR interact with G-proteins, and that multiple contacts with these receptor domains may be important for binding and activation of the G-proteins.
authors.affiliation: Department of Medicine, Division of Cardiology, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: H
authors.initials: H
authors.lastname: Kai
authors.forename: R W
authors.initials: RW
authors.lastname: Alexander
authors.forename: M
authors.initials: M
authors.lastname: Ushio-Fukai
authors.forename: P R
authors.initials: PR
authors.lastname: Lyons
authors.forename: M
authors.initials: M
authors.lastname: Akers
authors.forename: K K
authors.initials: KK
authors.lastname: Griendling
mesh_terms: D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors; D019204:GTP-Binding Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D008024:Ligands; D008297:Male; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D008024:Ligands; D010455:Peptides; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins