The metabolism of inositol 4-monophosphate in rat mammalian tissues.
Rat brain soluble fraction contains an enzymatic activity that dephosphorylates inositol 1,4-bisphosphate (Ins(1,4)P2). We have used anion exchange h.p.l.c. in order to identify the inositol monophosphate product of Ins(1,4)P2 hydrolysis (i.e. Ins(1)P1, Ins(4)P1 or both). When [3H]Ins(1,4)P2 was used as substrate, we obtained an inositol monophosphate isomer that was separated from the co-injected standard [3H]Ins(1)P1. This suggested an Ins(1,4)P21-phosphatase pathway leading to the production of the inositol 4-monophosphate isomer. The dephosphorylation of [32P]Ins(4)P1 was measured in rat brain, liver and heart soluble fraction and was Li+-sensitive. Chromatography of the soluble fraction of a rat brain homogenate on DEAE-cellulose resolved a monophosphate phosphatase activity that hydrolyzed both [3H]Ins(1)P1 and [4-32P]Ins(4)P1 isomers.
D000818:Animals; D001921:Brain / Q000201:enzymology*; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D051381:Rats; D013403:Sugar Phosphates / Q000378:metabolism*; D014316:Tritium
D007295:Inositol Phosphates; D010761:Phosphorus Radioisotopes; D013403:Sugar Phosphates; D014316:Tritium; C045537:inositol 4-phosphate; D010744:Phosphoric Monoester Hydrolases; C053087:inositol-1,4-bisphosphate 1-phosphatase