Abstract: | The guanosine-5-triphosphate (GTP) binding of D1-dopamine (DA) receptor agonist [H3]-SKF 38393 is described. The binding of [H3]-SKF 38393 occurs in two different DA receptors in the presence of guanylyl nucleotides, and in one receptor population in the absence of guanylyl nucleotides. It was shown with GDP--P33 binding analysis that G proteins in the mollusc nervous tissue membranes accelerate exchange of guanosine-5-diphosphate (GDP) for GTP considerably. While binding of [H3]-SKF 38393 was not found with phosphorylation of the membranes by the catalytic subunit of cAMP-dependent protein kinase A, basal and DA-induced GDP GTP exchange was noticeably inhibited with phosphylation in the nervous tissue membranes.A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 4, pp. 451–461, July–August, 1992. |