Guanine nucleotide regulation of B2 kinin receptors. Time-dependent formation of a guanine nucleotide-sensitive receptor state from which [3H]bradykinin dissociates slowly
Research output: Contribution to journal › Article
We have examined the binding of [3H]bradykinin to bovine myometrial membranes and assessed its sensitivity to guanine nucleotides. Total binding displayed a typical B2 kinin receptor specificity. However, saturation binding isotherms were resolved into at least two components with K(D) values of 8 pM (45%) and 378 pM (55%). Low affinity binding exhibited relatively rapid rates of association (k(obs) = 1.40 x 10-2 s-1) and dissociation (k-1 = 3.82 x 10-3 s-1), while high affinity binding exhibited considerably slower rates (k(obs) = 9.52 x 10-4 s-1 and k-1 = 4.43 x 10-5 s-1). Pre-equilibrium dissociation kinetics revealed that formation of high affinity binding was characterized as a time-dependent accumulation of the slow dissociation rate at the expense of at least one other more rapid dissociation rate. In the presence of 10 μM guanyl-5'-yl imidodiphosphate (Gpp(NH)p), at least two binding components were resolved with K(D) values of 37 pM (12%) and 444 pM (88%). Gpp(NH)p apparently specifically perturbed high affinity binding by completely preventing the accumulation of the slow dissociation phase. Instead, two more rapid dissociation rates (k-1 = 8.53 x 10-3 s-1 and 4.43 x 10-4 s-1) were observed. These results suggest that [3H]bradykinin interacts with at least two B2 kinin receptor-like binding sites in bovine myometrial membranes. A three-state model for the guanine nucleotide-sensitive agonist interaction with the high affinity binding sites is proposed.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 1990 Jul 9|