The binding of [3H]R-PIA to A1 adenosine receptors produces a conversion of the high- to the low-affinity state |
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Authors: | V Casadó J Mallol E I Canela C Lluis R Franco |
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Affiliation: | Departament de Bioquimica i Fisiologia, Facultat de Quimica, Barcelona, Catalunya, Spain. |
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Abstract: | Kinetic evidence for negative cooperativity on the binding of [3H]R-PIA to A1 adenosine receptors was obtained from dissociation experiments at different ligand concentrations and from the equilibrium isotherm. The dissociation curves indicate that there is an apparent ligand-induced transformation of high- to low-affinity states of the receptor. At concentrations of 18.2 nM R-PIA or higher there was only found the low-affinity state of the receptor. In view of these results equilibrium binding data were analyzed by the usual two-state model (assuming that there is an interconversion between them) and by the negative cooperativity model employing the Hill equation. |
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