In solubilized bovine brain membrane preparations AlF4- (20 μM AlCl3 plus 10 mM NaF) and 50 nM guanosine 5-O-(2-thiotriphosphate) (GTPγS) promoted a rapid but transient inhibition of phospholipase C (PLC) activity. Maximal inhibition was evident within 7 min of incubation, followed by reversal of inhibition. In contrast, 10 μM GTPγS did not induce inhibition of PLC activity but rather produced a time-dependent stimulation of PLC activity. GTPγS-dependent inhibition of PLC activity was concentration-dependent with half-maximal inhibition at 1 nM. Inhibition was antagonized by guanosine 5-O-(2-thiodiphosphate (GDPβS). Pertussis toxin delayed the onset of inhibition by GTPγS but did not prevent the inhibitory effect. αo-GTPγS or αo-GDP had little effect on PLC activity. αi-GTPγS and αi-GDP produced a 15% inhibition of PLC activity. βγ subunits did not inhibit basal PLC activity but did attenuate the net degree of inhibition due to GTPγS. Inhibition was associated with a decrease in the Ca2+ sensitivity of PLC. Preincubation of membranes with anti-PLC-β1 antibody, but not anti-PLC-γ1 or anti-PLC-δ1, prevented the GTPγS-mediated inhibition of PLC. These studies implicate PLC-β1 as an effector system that is under negative modulation by a G protein-dependent mechanism.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - 1993|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology