Proteolytic modification of membrane-associated phospholipase C-beta by mu-calpain enhances its activation by G-protein beta gamma subunits in human platelets.
Membrane-associated phosphoinositide-phospholipase C (PI-PLC)-beta (150 kDa) and its truncated forms (100 kDa and 45 kDa) were purified from human platelets. The 100 kDa PI-PLC-beta was found to be activated to a greater extent by brain G-protein beta gamma subunits compared to the intact 150 kDa enzyme. Furthermore, treatment with mu-calpain of the intact PI-PLC-beta (150 kDa) caused a marked augmentation of its activation by beta gamma subunits. This enhanced PLC activation by beta gamma subunits was due to truncation by mu-calpain, producing a 100 kDa PI-PLC, but not by another protease, thrombin.
Banno
Y
Y
Department of Biochemistry, Gifu University School of Medicine, Japan.
Asano
T
T
Nozawa
Y
Y
D001792:Blood Platelets / Q000201:enzymology* / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000378:metabolism*; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*
D008565:Membrane Proteins; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D002154:Calpain; D019204:GTP-Binding Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase