Regulation of fructose-6-phosphate 2-kinase by phosphorylation and dephosphorylation: Possible mechanism for coordinated control of glycolysis and glycogenolysis

E. Furuya, M. Yokoyama, K. Uyeda

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Abstract

The kinetic properties and the control mechanism of fructose-6-phosphate 2-kinase (ATP: D-fructose-6-phosphate 2-phosphotransferase) were investigated. The molecular weight of the enzyme is ≃ 100,000 as determined by gel filtration. The plot of initial velocity versus ATP concentration is hyperbolic with a K(m) of 1.2 mM. However, the plot of enzyme activity as a function of fructose 6-phosphate is sigmoidal. The apparent K(0.5) for fructose 6-phosphate is 20 μM. Fructose-6-phosphate 2-kinase is inactivated by the catalytic subunit of cyclic AMP-dependent protein kinase, and the inactivation is closely correlated with phosphorylation. The enzyme is also inactivated by phosphorylase kinase in the presence of Ca2+ and calmodulin. The phosphorylated fructose-6-phosphate 2-kinase, which is inactive, is activated by phosphorylase phosphatase and alkaline phosphatase. The possible physiological significance of these observations in the coordinated control of glycogen metabolism and glycolysis is discussed.

Original languageEnglish (US)
Pages (from-to)325-329
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume79
Issue number2 I
DOIs
StatePublished - Jan 1 1982

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