Regulation of polyphosphoinositide-specific phospholipase C activity by purified Gq.
The hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) by phospholipase C yields the second messengers inositol 1,4,5-trisphosphate (InsP3) and 1,2-diacylglycerol. This activity is regulated by a variety of hormones through G protein pathways. However, the specific G protein or proteins involved has not been identified. The alpha subunit of a newly discovered pertussis toxin-insensitive G protein (Gq) has recently been isolated and is now shown to stimulate the activity of polyphosphoinositide-specific phospholipase C (PI-PLC) from bovine brain. Both the maximal activity and the affinity of PI-PLC for calcium ion were affected. These results identify Gq as a G protein that regulates PI-PLC.
Smrcka
A V
AV
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235.
Hepler
J R
JR
Brown
K O
KO
Sternweis
P C
PC
D000535:Aluminum / Q000494:pharmacology; D017607:Aluminum Compounds; D000818:Animals; D002118:Calcium / Q000502:physiology; D002417:Cattle; D004789:Enzyme Activation / Q000187:drug effects; D005459:Fluorides / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000502:physiology*; D006153:Guanosine Diphosphate; D066298:In Vitro Techniques; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D013379:Substrate Specificity
D017607:Aluminum Compounds; D006153:Guanosine Diphosphate; D000535:Aluminum; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D019204:GTP-Binding Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D005459:Fluorides; D002118:Calcium; C032311:aluminum fluoride