A G protein mutant that inhibits thrombin and purinergic receptor activation of phospholipase A2.
The stimulation of phospholipase A2 by thrombin and type 2 (P2)-purinergic receptor agonists in Chinese hamster ovary cells is mediated by the G protein Gi. To delineate alpha chain regulatory regions responsible for control of phospholipase A2, chimeric cDNAs were constructed in which different lengths of the alpha subunit of Gs (alpha s) were replaced with the corresponding sequence of the Gi alpha subunit (alpha i2). When a carboxyl-terminal chimera alpha s-i(38), which has the last 38 amino acids of alpha s substituted with the last 36 residues of alpha i2, was expressed in Chinese hamster ovary cells, the receptor-stimulated phospholipase A2 activity was inhibited, although the chimera could still activate adenylyl cyclase. Thus, alpha s-i(38) is an active alpha s, but also a dominant negative alpha i molecule, indicating that the last 36 amino acids of alpha i2 are a critical domain for G protein regulation of phospholipase A2 activity.
Gupta
S K
SK
Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.
Diez
E
E
Heasley
L E
LE
Osawa
S
S
Johnson
G L
GL
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002460:Cell Line; D002712:Chlorides / Q000494:pharmacology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology; D018021:Lithium Chloride; D046911:Macromolecular Substances; D009154:Mutation; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D015183:Restriction Mapping; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014162:Transfection
D001095:Arachidonic Acids; D002712:Chlorides; D007295:Inositol Phosphates; D046911:Macromolecular Substances; D011983:Receptors, Purinergic; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D008094:Lithium; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D013917:Thrombin; D019204:GTP-Binding Proteins; D018021:Lithium Chloride