Contribution of different protein phosphatases to the dephosphorylation of 6-phosphofructo-1-kinase and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase in rat liver.
The nature of rat liver protein phosphatases involved in the dephosphorylation of the glycolytic key enzyme 6-phosphofructo-1-kinase and the regulatory enzyme 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase was investigated. In terms of the classification system proposed by Ingebritsen & Cohen [(1983) Eur. J. Biochem. 132, 255-261], only the type-2 protein phosphatases 2A (which can be separated into 2A1 and 2A2) and 2C act on these substrates. Fractionation of rat liver extracts by anion-exchange chromatography and gel filtration revealed that protein phosphatase 2A is responsible for most of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase phosphatase activity (activity ratio 2A/2C = 4:1). On the other hand, 6-phosphofructo-1-kinase phosphatase activity is equally distributed between protein phosphatases 2A (2A1 plus 2A2) and 2C. In addition, the possible role of low-Mr compounds for the control of purified protein phosphatase 2C was examined. At near-physiological concentrations, none of the metabolites studied significantly affected the rate of dephosphorylation of 6-phosphofructo-1-kinase, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, pyruvate kinase or fructose-1,6-bisphosphatase.
Mieskes
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Söling
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D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003600:Cytosol / Q000201:enzymology; D008099:Liver / Q000201:enzymology*; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D025481:Phosphofructokinase-2; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000302:isolation & purification; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D054648:Protein Phosphatase 2; D051381:Rats
D017853:Phosphotransferases (Alcohol Group Acceptor); D025481:Phosphofructokinase-2; D010732:Phosphofructokinase-1; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D010765:Phosphorylase Phosphatase; D010744:Phosphoric Monoester Hydrolases