57 research outputs found
The novel inositol lipid phosphatidylinositol 3,4-bisphosphate is produced by human blood platelets upon thrombin stimulation
Tyrosine kinases and phosphoinositide metabolism in thrombin-stimulated human platelets
An Uncommon Multiphosphorylated Lipid in Neurospora-Crassa Whose Formation Is Catalyzed Invitro by a Calcium-Dependent and Phospholipid-Dependent Kinase
The presence of a calcium- and phospholipid-dependent kinase activity in the soluble extracts of Neurospora crassa has been reported earlier. This activity phosphorylated in vitro two endogenous substrates, one of apparent molecular weight (M(r)) 85 000, the other much lower than 14 000. This paper reports that the smaller substrate is a lipid. The lower M(r) phosphorylated compound could be extracted from proteins by organic solvents. Various thin-layer chromatographic analyses revealed that it did not comigrate with any of the phospholipids tested. Chemical and enzymatic structural analyses indicated that the phosphorylated compound was sensitive to mild alkaline methanolysis, alkaline phosphatase and phospholipase A1 but resistant to phospholipases A2, C and D or nitrous acid treatment. A similar compound was detected in the organic phase after extraction of N. crassa mycelia labelled in vivo with either (P(i))-P-32 or [H-3]glycerol. It could not be detected when [H-3]inositol was used as label. The addition of in vivo P-32-labelled lipids in phosphorylation reactions revealed that the low M(r) substrate of the calcium- and phospholipid-dependent kinase already contained some phosphate which was itself sensitive to alkaline phosphatase. An identical apolar component was generated by alkaline phosphatase treatment of both the substrate of the kinase and the phosphorylated substrate. From these data it is concluded that the low M(r) phosphorylated compound is a lipid, presumably consisting of a diacylglycerol backbone with an as yet undetermined structure linked to the glycerol moiety. This structure contains at least two phosphate groups
Characterization and properties of a phosphatidylinositol phosphodiesterase (phospholipase C) from platelet cytosol
Subcellular localization of inositol lipids in blood platelets as deduced from the use of labelled precursors
Evidence for a glycoprotein IIb-IIIa and aggregation-independent mechanism of phosphatidylinositol 3',4' bisphosphate synthesis in human platelets
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