Isolation of 1-monomethylphosphoinositol 4,5-bisphosphate [a product of methanolysis of inositol 1,2-(cyclic)-4,5-trisphosphate] from Swiss mouse 3T3 cells.
We have noted two previously undescribed inositol polyphosphates in neutral methanol extracts from Swiss mouse 3T3 cells that were grown in [3H]inositol and stimulated with platelet-derived growth factor. They have been identified as 1-monomethylphosphoinositol 4,5-bisphosphate and 1-monomethylphosphoinositol 4-phosphate by comparison to a synthesized standard using HPLC chromatography, paper electrophoresis, and enzymatic dephosphorylation with inositol polyphosphate 5-phosphomonoesterase and intestinal alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1]. We propose that these compounds are formed by methanolysis of inositol 1,2-(cyclic)-4,5-trisphosphate and inositol 1,2-(cyclic)-4-bisphosphate present in the cells. Inositol cyclic phosphates did not react with neutral methanol in the absence of the cells, which are required for the methanolysis reaction. These findings suggest a role for inositol cyclic phosphates as reactive compounds that are added to as yet unidentified cellular acceptors.
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Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110.
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Majerus
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D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D002854:Chromatography, Paper; D004590:Electrophoresis, Paper; D007294:Inositol / Q000378:metabolism; D007295:Inositol Phosphates / Q000302:isolation & purification* / Q000378:metabolism*; D051379:Mice; D013403:Sugar Phosphates / Q000302:isolation & purification* / Q000378:metabolism*; D014316:Tritium
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D014316:Tritium; C054657:1-monomethylphosphoinositol 4,5-bisphosphate; D007294:Inositol; C049924:inositol-1,2-cyclic-4,5-triphosphate