Role of G proteins in activation of phosphoinositide phospholipase C.
The pertussis toxin-insensitive G proteins that stimulate phosphoinositide phospholipase C consist of 42- and 43-kDa alpha-subunits, 35-kDa beta-subunits and 8-kDa gamma-subunits. The alpha-subunits have been identified as alpha q and alpha 11, and both specifically stimulate the beta 1 isozyme of the phospholipase. Activation of Ca(2+)-mobilizing receptors in liver plasma membranes selectively induces the labelling of alpha q and alpha 11 by [alpha-32P]GTP-azidoanilide. Reconstitution of Gq and G11 with M1 muscarinic receptor and the beta 1 isozyme allows GTP gamma S-dependent stimulation of PtdInsP2 hydrolysis by carbachol. These data establish unequivocally that Gq and G11 function as the transducing G proteins for Ca(2+)-mobilizing receptors.
Exton
J H
JH
Howard Hughes Medical Institute, Vanderbilt University, Nashville, Tennessee 37232.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010716:Phosphatidylinositols / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism; D015398:Signal Transduction
D007527:Isoenzymes; D010716:Phosphatidylinositols; D011956:Receptors, Cell Surface; D011976:Receptors, Muscarinic; D010727:Phosphoric Diester Hydrolases; D019204:GTP-Binding Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002118:Calcium