GTP gamma S-stimulated hydrolysis of phosphatidylinositol-4,5-bisphosphate soluble phospholipase C from human platelets requires soluble GTP-binding protein.
GTP-binding activity was fractionated into two peaks (GI and GII) by chromatography on heparin-agarose. GTP-dependent PLC activity eluted as a single peak, which co-chromatographed with GTP-binding peak GII. Rechromatography of peak GII on heparin-agarose, in the presence of 0.5% sodium cholate, resulted in separation of PLC and GTP-binding activities, and loss of GTP-dependent PLC activity. Recombining fractions containing PLC and GTP-binding activities restored GTP-dependent PLC activity. A specific GTP-binding protein of 29,000 daltons was identified in peak GII by Western blotting of column fractions with [alpha-32P]GTP. These results demonstrate that the soluble phospholipase C from human platelets is regulated by GTP S-binding protein (G29).
Baldassare
J J
JJ
American Red Cross, Bi-State Chapter, St. Louis, Mo. 63108.
Knipp
M A
MA
Henderson
P A
PA
Fisher
G J
GJ
D001792:Blood Platelets / Q000201:enzymology*; D002846:Chromatography, Affinity; D003600:Cytosol / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000097:blood* / Q000302:isolation & purification; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism*; D011485:Protein Binding; D013873:Thionucleotides / Q000097:blood / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000097:blood*
D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins