Publications (2)7.32 Total impact
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Article: Lys(199) mutation of the human angiotensin type 1 receptor differentially affects the binding of surmountable and insurmountable non-peptide antagonists.
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ABSTRACT: Many slow dissociating (insurmountable) non-peptide angiotensin type 1 receptor (AT1) antagonists contain,besides the acidic biphenyltetrazole substructure of losartan, a second acidic group to stabilise antagonist-receptor complexes. To investigate the involved basic amino-acids of the human AT1-receptor, wild-type and mutant receptors were transiently transfected in CHO-K1 cells and characterised by [3H]candesartan binding. Lys199-->Gln substitution decreased the affinity 45-fold for candesartan (95% insurmountable),18-fold for EXP3174 (70% insurmountable), 10-fold for irbesartan (40% insurmountable) and 5-fold for losartan (surmountable). His256 -->Ala substitution had only minor effects. This suggests that Lys199 is important for the tight binding of non-peptide antagonists.Journal of Renin-Angiotensin-Aldosterone System 09/2000; 1(3):283-8. · 2.44 Impact Factor -
Article: Shallow agonist competition binding curves for beta-adrenergic receptors: the role of tight agonist binding.
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ABSTRACT: The beta 2-adrenergic receptors of bovine trapezius muscle membranes demonstrate tight agonist binding as a result of the formation of complexes between agonists, receptors, and Ns. Preincubation of the membranes with (-)-isoproterenol (followed by washing) causes a time- and concentration-dependent decrease in the number of radioligand-binding sites to a plateau value of 41.5 +/- 4%. The affinity of the remaining sites for the radioligand (-)-[3H]dihydroalprenolol is unchanged. This decrease is stable under radioligand binding conditions but is readily reversed in the presence of GTP. The isoproterenol/(-)-[3H]dihydroalprenolol competition binding curves are shallow. Such a phenomenon is usually interpreted in terms of two interconvertible affinity states of the receptor: the high affinity state reflecting the coupling of the agonist X receptor complex to Ns and the low affinity state not interacting with Ns. However, the competition curves undergo time-dependent shifts to the left. This apparent non-equilibrium can be explained by a model in which tight agonist binding to part of the receptor population is included. The usual computerized interpretation of the competition binding curves do not allow the correct evaluation of agonist binding parameters in the presence of tight agonist binding.Molecular Pharmacology 02/1987; 31(1):69-73. · 4.88 Impact Factor
