Dephosphorylation of 1d -myo-inositol 1,4-bisphosphate in rat liver
| Autor: | Diane J. Storey, Andrew J. Morris, C P Downes, Robert H. Michell |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Inositol Phosphates
Ion chromatography Phosphatase Inositol monophosphatase Lithium Biochemistry Dephosphorylation chemistry.chemical_compound Cytosol Animals Inositol Molecular Biology chemistry.chemical_classification biology Cell Biology Chromatography Ion Exchange Phosphoric Monoester Hydrolases Rats Enzyme Liver chemistry biology.protein Sugar Phosphates Uncompetitive inhibitor Subcellular Fractions Research Article |
| Zdroj: | Biochemical Journal. 254:655-660 |
| ISSN: | 1470-8728 0264-6021 |
| DOI: | 10.1042/bj2540655 |
| Popis: | Dephosphorylation of 1D-myo-inositol 1,4-bisphosphate [Ins(1,4)P2] in rat liver is catalysed by a cytosolic phosphatase that removes the 1-phosphate group. The Km for Ins(1,4)P2 is approx. 17 microM. Li+ (100 mM) causes 50% inhibition of Ins(1,4)P2 phosphatase activity when activity is measured at the very low substrate concentration of 10 nM, but on raising the substrate concentration to 100 microM there is a greater than 10-fold increase in sensitivity to Li+, suggesting that Li+ acts mainly, but not entirely, as an uncompetitive inhibitor of Ins(1,4)P2 phosphatase. In addition, rat liver cytosol shows Li+-sensitive phosphatase activity against 1D-myo-inositol 1-,3- and 4-monophosphates. The Ins(1,4)P2 1-phosphatase and inositol monophosphatase activities all share an apparent Mr of 47 x 10(3), as determined by gel-filtration chromatography. However, the Ins(1,4)P2 1-phosphatase is more sensitive to inactivation by heat, and can be separated from inositol monophosphatase activity by anion-exchange chromatography. We conclude that rat liver cytosol contains an Ins(1,4)P2 1-phosphatase that is distinct from, but in many ways similar to, inositol monophosphatase. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|