G protein-mediated inhibition of phospholipase C activity in a solubilized membrane preparation

I. Litosch, I. Sulkholutskaya, C. Weng

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20 Scopus citations

Abstract

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 languageEnglish (US)
Pages (from-to)8692-8697
Number of pages6
JournalJournal of Biological Chemistry
Volume268
Issue number12
StatePublished - 1993

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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