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

• Published in: Biochemical journal Vol. 225; no. 3; pp. 665 - 670
• Main Authors: Mieskes, G, Söling, H D
• Format: Journal Article
• Language: English
• Published: England 01.02.1985
• Subjects: Animals; Chromatography, DEAE-Cellulose; Chromatography, Gel; Cytosol - enzymology; Liver - enzymology; Phosphofructokinase-1 - metabolism; Phosphofructokinase-2; Phosphoprotein Phosphatases - isolation & purification; Phosphoprotein Phosphatases - metabolism; Phosphoric Monoester Hydrolases - metabolism; Phosphorylase Phosphatase - isolation & purification; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Protein Phosphatase 2; Rats
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2250665

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.