Rat liver plasma membranes reconstituted with bovine brain phospholipase C β1 (PLC-β1) exhibit a dual regulation of PLC-β1 activity by G-proteins. Guanosine 5´-[γ-thio]triphosphate (GTP[S]; 0.1 nM) produced a 20-25% inhibition of PLC-β1 activity within 7 min of incubation. The addition of vasopressin resulted in near-basal levels of activity in the presence of 0.1 nM GTP[S]. Clonidine had little effect on the net inhibition due to GTP[S]. A similar antagonism between carbachol and GTP[S] occurred in cerebral cortical membranes containing endogenous PLC-β1 activity. αo/i-GDP (a mixture of GDP-liganded Goα and Giα) attenuated the GTP[S]-dependent inhibition of PLC-β1 whereas αo/i-GTP[S] had no effect, suggesting an involvement of G-protein βγ subunits in the inhibition of PLC-β1. Low concentrations of βγ subunits inhibited PLC-β1 activity. Inhibition was followed by reversal to basal activity and onset of stimulation as the βγ concentration was increased. Inhibition by βγ was dependent on the presence of membranes. These results indicate that G-protein βγ subunits constitute a mechanism by which G-proteins mediate a rapid and transient inhibition of PLC-β1.
Research Article| October 01 1996
G-protein inhibition of phospholipase C-β1 in membranes: role of G-protein βγ subunits
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Irene LITOSCH; G-protein inhibition of phospholipase C-β1 in membranes: role of G-protein βγ subunits. Biochem J 1 October 1996; 319 (1): 173–178. doi: https://doi.org/10.1042/bj3190173
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