Mutation of Asp74 of the rat angiotensin II receptor confers changes in antagonist affinities and abolishes G-protein coupling
| Autor: | Eleanor Davies, Claire Bihoreau, Eric Clauser, Catherine Monnot, Pierre Corvol, Kenneth E. Bernstein, Betty Teutsch |
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| Rok vydání: | 1993 |
| Předmět: |
Agonist
Angiotensin receptor Angiotensins G protein medicine.drug_class Inositol Phosphates Molecular Sequence Data Restriction Mapping Angiotensin III CHO Cells Sodium Chloride Biology Transfection Polymerase Chain Reaction Cytosol GTP-Binding Proteins Cricetinae medicine Animals Amino Acid Sequence Receptor Aspartic Acid Receptors Angiotensin Multidisciplinary Base Sequence Angiotensin II Molecular biology Rats Kinetics Transmembrane domain Oligodeoxyribonucleotides Biochemistry Mutagenesis Site-Directed Calcium Signal transduction Research Article |
| Zdroj: | Proceedings of the National Academy of Sciences. 90:5133-5137 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.90.11.5133 |
| Popis: | Aspartic acid in the second transmembrane domain is a highly conserved amino acid among the G protein-coupled receptors and is functionally important for agonist binding and G-protein coupling in beta 2-adrenergic and luteinizing hormone receptors. To determine whether this aspartic acid is also involved in the function of the rat vascular angiotensin II receptor subtype 1 (AT1a), Asp74 was replaced either by asparagine or by glutamic acid. When expressed in CHO cells, the two mutants and the wild-type receptor displayed similarly high affinities for the agonist [Sar1, Tyr(125I)4]angiotensin II [where Sar is sarcosine and Tyr(125I) is monoiodinated tyrosine] and the other agonists: ([Sar1]angiotensin II > angiotensin II > angiotensin III >> angiotensin I). However, the Asn74 mutant shows striking differences in its affinity for some antagonists when compared with the wild-type receptor: the affinity for DUP753 was decreased 10-fold, whereas it was increased 6-fold for [Sar1,Ala8]angiotensin II and 20-fold for CGP42112A. These pharmacological changes were associated with a major defect in transmembrane signaling, since angiotensin II was unable to stimulate inositol phosphate production and increase cytosolic Ca2+ concentration through the two mutated receptors, whereas a clear dose-dependent stimulation was observed in cells expressing the wild-type receptor. Angiotensin II was able to promote DNA synthesis through the wild type but not through the mutated receptors. These data indicate that the conserved Asp74 residue of the AT1a receptor is important for the binding of angiotensin II antagonists and is essential for the transmembrane signaling cascade. |
| Databáze: | OpenAIRE |
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