The dephosphorylation pathway of D-myo-inositol 1,3,4,5-tetrakisphosphate in rat brain.
Dephosphorylation of inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] was measured in both the soluble and the particulate fractions of rat brain homogenates. Analysis of the hydrolysis of [4,5-32P]Ins(1,3,4,5)P4 showed that for both fractions the 5-phosphate of Ins(1,3,4,5)P4 was removed and inositol 1,3,4-trisphosphate [Ins(1,3,4)P3] was specifically produced. In the soluble fraction, Ins(1,3,4)P3 was further hydrolysed at the 1-phosphate position to inositol 3,4-bisphosphate[Ins(3,4)P2]. DEAE-cellulose chromatography of the soluble fraction separated the phosphatase activities into three peaks. The first hydrolysed both Ins(1,3,4,5)P4 and inositol 1,4,5-trisphosphate, the second inositol 1-phosphate and the third Ins(1,3,4)P3 and inositol 1,4-bisphosphate, [Ins(1,4)P2]. Further purification of the third peak on either Sephacryl S-200 or Blue Sepharose could not dissociate these two activities [i.e. with Ins(1,4)P2 and Ins(1,3,4)P3 as substrates]. The dephosphorylation of Ins(1,3,4)P3 could be inhibited by the addition of Li+.
Erneux
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Institute of Interdisciplinary Research (IRIBHN), School of Medicine, Free University of Brussels, Belgium.
Delvaux
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Moreau
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Dumont
J E
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D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology; D002848:Chromatography, DEAE-Cellulose; D002851:Chromatography, High Pressure Liquid; D006868:Hydrolysis; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D000072181:Inositol Polyphosphate 5-Phosphatases; D008094:Lithium / Q000494:pharmacology; D018021:Lithium Chloride; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D012995:Solubility; D013379:Substrate Specificity; D013403:Sugar Phosphates / Q000378:metabolism*
D002712:Chlorides; D007295:Inositol Phosphates; D013403:Sugar Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D008094:Lithium; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; D018021:Lithium Chloride