Dependence of coupling of dopamine receptors with G-proteins on the status of sulfhydryl groups in membrane proteins

Features of dopamine receptors coupling to G-proteins in the plasma membranes from neural tissue of the mollusc Lymnaea stagnalis were studied. Radioligand binding analysis of [3H]-dopamine and investigation of the GTPase activity have showed that dopamine receptors both inhibit and stimulate coupled G-proteins. It have been found that changing of sulfhydril groups state of the membrane proteins modulates interaction of dopamine receptors with G-proteins. The inhibitory influence of dopamine receptors on the coupled to them G-proteins is potentiated by reduction of thiol groups.