Stimulation of phospholipase C by guanine-nucleotide-binding protein beta gamma subunits

Eur J Biochem. 1992 Jun 15;206(3):821-31. doi: 10.1111/j.1432-1033.1992.tb16990.x.


We have previously shown that soluble fractions obtained from human HL-60 granulocytes contain a phospholipase C which is markedly stimulated by the stable GTP analogue guanosine 5'-[3-O-thio]triphosphate (Camps, M., Hou, C., Jakobs, K. H. and Gierschik, P. (1990) Biochem. J. 271, 743-748]. To investigate whether this stimulation was due to a soluble alpha subunit of a heterotrimeric guanine-nucleotide-binding protein or a soluble low-molecular-mass GTP-binding protein, we have examined the effect of purified guanine-nucleotide-binding protein beta gamma dimers on the phospholipase-C-mediated formation of inositol phosphates by HL-60 cytosol. We found that beta gamma subunits, purified from bovine retinal transducin (beta gamma t), markedly stimulated the hydrolysis of phosphatidylinositol 4,5-bisphosphate by this phospholipase C preparation. The stimulation of phospholipase C by beta gamma t was not secondary to a phospholipase-A2-mediated generation of arachidonic acid, was prevented by the GDP-liganded transducin alpha subunit and was additive to activation of phospholipase C by guanosine 5'-[3-O-thio]triphosphate. Beta gamma t also stimulated soluble phospholipase C from human and bovine peripheral neutrophils, as well as membrane-bound, detergent-solubilized phospholipase C from HL-60 cells. Stimulation of soluble HL-60 phospholipase C was not restricted to beta gamma t, but was also observed with highly purified beta gamma subunits from bovine brain. Fractionation of HL-60 cytosol by anion-exchange chromatography revealed the existence of at least two distinct forms of phospholipase C in HL-60 granulocytes. Only one of these forms was sensitive to stimulation by beta gamma t, demonstrating that stimulation of phospholipase C by beta gamma subunits is isozyme specific. Taken together, our results suggest that guanine-nucleotide-binding protein beta gamma subunits may play an important and active role in mediating the stimulation of phospholipase C by heterotrimeric guanine-nucleotide-binding proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonic Acid / metabolism
  • Brain Chemistry
  • Cattle
  • Cytosol / enzymology
  • GTP-Binding Proteins / physiology*
  • Granulocytes / enzymology
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Humans
  • Inositol Phosphates / metabolism
  • Isoenzymes / metabolism
  • Macromolecular Substances
  • Neutrophils / enzymology
  • Phospholipases A / metabolism
  • Phospholipases A2
  • Tumor Cells, Cultured
  • Type C Phospholipases / metabolism*


  • Inositol Phosphates
  • Isoenzymes
  • Macromolecular Substances
  • Arachidonic Acid
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Phospholipases A
  • Phospholipases A2
  • Type C Phospholipases
  • GTP-Binding Proteins