Isozyme-selective stimulation of phospholipase C-beta 2 by G protein beta gamma-subunits

Nature. 1992 Dec 17;360(6405):684-6. doi: 10.1038/360684a0.


Hydrolysis by phospholipase C (PLC) of phosphatidylinositol 4,5-bisphosphate is a key mechanism by which many extracellular signalling molecules regulate functions of their target cells. At least eight distinct isozymes of PLC are recognized in mammalian cells. Receptor-controlled PLC is often regulated by G proteins, which can be modified by pertussis toxin in some cells but not in others. In the latter cells, PLC-beta 1, but not PLC-gamma 1 or PLC-delta 1, may be activated by members of the alpha q-subfamily of the G protein alpha-subunits. An unidentified PLC in soluble fractions of cultured human HL-60 granulocytes is specifically stimulated by G protein beta gamma subunits purified from retina and brain. Identification of a second PLC-beta complementary DNA (PLC-beta 2) in an HL-60 cell cDNA library prompted us to investigate the effect of purified G protein beta gamma subunits on the activities of PLC-beta 1 and PLC-beta 2 transiently expressed in cultured mammalian cells. We report here that PLC-beta 1 and PLC-beta 2 were stimulated by free beta gamma subunits and that PLC-beta 2 was the most sensitive to beta gamma stimulation. Thus stimulation of PLC by beta gamma subunits is isozyme-selective and PLC-beta 2 is a prime target of beta gamma stimulation. Activation of PLC-beta 2 by beta gamma subunits may be an important mechanism by which pertussis toxin-sensitive G proteins stimulate PLC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • GTP-Binding Proteins / metabolism*
  • Genetic Vectors
  • Inositol Phosphates / metabolism
  • Isoenzymes / genetics
  • Isoenzymes / metabolism*
  • Kinetics
  • Macromolecular Substances
  • Plasmids
  • Recombinant Proteins / metabolism
  • Transfection
  • Type C Phospholipases / genetics
  • Type C Phospholipases / metabolism*


  • Inositol Phosphates
  • Isoenzymes
  • Macromolecular Substances
  • Recombinant Proteins
  • Type C Phospholipases
  • GTP-Binding Proteins