Rat liver plasma membranes reconstituted with bovine brain PLCβ, exhibit a dual regulation of PLC-β, activity by G proteins. Low concentrations of GTP-γ-S inhibited PLC-β, activity while high concentrations of GTP-γ-S stimulated PLC-β, activity. In the presence of GTP, the α2-selective adrenergic agonists, clonidine and oxymethazoline, inhibited PLC-β1 activity. The aminosteroid U-73122 blocked PLC-β1 inhibition by GTP plus clonidine and the stimulation due to GTP-γ-S plus vasopressin. αo/iGDP attenuated the GTP-γ-S dependent inhibition of PLC-β, while αo/iGTP-γ-S had no effect suggesting an involvement of G protein βγ subunits in the inhibitory mechanism. Low concentrations of βγ subunits inhibited PLC-β1 activity. Inhibition was followed by reversal to basal and onset of stimulation as the βγ concentration was increased. Inhibition by βγ was dependent on the presence of membranes. Treatment of membranes with anti-αq/11 antibody attenuated the βγ inhibition. These results indicate that the rapid and transient inhibition of PLC-β1 which occurs at low ligand concentrations may be mediated through βγ subunits and occurs through a mechanism which is dependent on αq.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology