Rat liver contains a potent endogenous inhibitor of inositol 1,3,4,5-tetrakisphosphate 3-phosphatase.
When Ins(1,3,4,5)P4 was incubated with a rat liver 100,000 g supernatant, about 93% of the substrate was metabolized by a 5-phosphatase, and only 7% by a 3-phosphatase. Ion-exchange chromatography of the supernatant specifically increased its 3-phosphatase activity 72 +/- 3-fold. This activated enzyme was inhibited by a heat-stable factor present in both the soluble and particulate portions of the cell.
Hodgson
M E
ME
Inositol Lipid Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709.
Shears
S B
SB
D000818:Animals; D002852:Chromatography, Ion Exchange; D004789:Enzyme Activation; D007295:Inositol Phosphates / Q000378:metabolism*; D000072181:Inositol Polyphosphate 5-Phosphatases; D008099:Liver / Q000032:analysis / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis / Q000037:antagonists & inhibitors*; D051381:Rats
D007295:Inositol Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; C064119:multiple inositol-polyphosphate phosphatase