Mutagenesis of the AT1 receptor reveals different binding modes of angiotensin II and [Sar1]-angiotensin II.
Homology modeling of the structure of the AT1 receptor, based on the high resolution rhodopsin crystal structure, indicated that it is unlikely that the binding of AngII to AT1 involves simultaneously all the receptor's residues reported in the literature to participate in this process. Site-directed mutagenesis using Ala substitution of charged residues Lys20, Arg23, Glu91 and Arg93 was performed to evaluate the participation of their side-chains in ligand binding and in triggering the cell's response. A comparative analysis by competition binding and functional assays using angiotensin II and the analog [Sar1]-angiotensin II suggests an important role for Arg23 of AT1 receptor in binding of the natural agonist. It is discussed whether some receptor's residues participate directly in the binding with AngII or whether they are part of a regulatory site.
Santos
Edson L
EL
Department of Biophysics, Escola Paulista de Medicina, UNIFESP, São Paulo 04023-062, Brazil.
Pesquero
João B
JB
Oliveira
Laerte
L
Paiva
Antonio C M
AC
Costa-Neto
Claudio M
CM
D019943:Amino Acid Substitution / Q000235:genetics; D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D006224:Cricetinae; D006801:Humans; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary; D044140:Receptor, Angiotensin, Type 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012243:Rhodopsin / Q000737:chemistry; D040681:Structural Homology, Protein
D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D012243:Rhodopsin