G protein regulation of phospholipase C activity in a membrane-solubilized system occurs through a Mg2+- and time-dependent mechanism

Irene Litosch

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

GTP-binding proteins have been implicated to function as key transducing elements in the mechanism underlying receptor activation of a membrane-associated phospholipase C activity. In the present study, the regulation of phospholipase C activity by GTP-binding proteins has been characterized in a detergent-solubilized system derived from bovine brain membranes. Guanosine-5′-(3-O-thio)triphosphate (GTP-γ-S) and guanyl-5′-yl imidodiphosphate (Gpp(NH)p) stimulated a dose-dependent increase in phospholipase C activity with half-maximal activation at 0.6 μM and 10 μM, respectively. The maximal degree of stimulation due to Gpp(NH)p or GTP-γ-S was comparable. 100 μM GTP had only a slight stimulatory effect on phospholipase C activity. Adenine nucleotides, 100 μM adenylyl-imidodiphosphate and ATP, did not stimulate phospholipase C activity, indicating that specific guanine nucleotide-dependent regulation of phospholipase C activity was preserved in the solubilized state. Gpp(NH)p or GTP-γ-S stimulation of phospholipase C activity was time-dependent and required Mg2+. Mg2+ regulated the time course for activation of phospholipase C by guanine nucleotides and the ability of guanine nucleotides to promote an increase in the Ca2+ sensitivity of phospholipase C. 200 μM GDP-β-S or 5 mM EDTA rapidly reversed the activation due to GTP-γ-S or Gpp(NH)p. These findings demonstrate that G protein regulation of phospholipase C activity in a bovine brain membrane- solubilized system occurs through a Mg2+ and time-dependent mechanism. Activation is readily reversible upon addition of excess GDP-β-S or removal of Mg2+.

Original languageEnglish
Pages (from-to)4764-4771
Number of pages8
JournalJournal of Biological Chemistry
Volume266
Issue number8
StatePublished - Mar 15 1991
Externally publishedYes

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Type C Phospholipases
GTP-Binding Proteins
Guanylyl Imidodiphosphate
Membranes
Guanosine Triphosphate
Chemical activation
Guanine Nucleotides
Brain
Adenylyl Imidodiphosphate
Guanosine 5'-O-(3-Thiotriphosphate)
Adenine Nucleotides
Edetic Acid
Detergents
Adenosine Triphosphate

ASJC Scopus subject areas

  • Biochemistry

Cite this

G protein regulation of phospholipase C activity in a membrane-solubilized system occurs through a Mg2+- and time-dependent mechanism. / Litosch, Irene.

In: Journal of Biological Chemistry, Vol. 266, No. 8, 15.03.1991, p. 4764-4771.

Research output: Contribution to journalArticle

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