J. Biol. Chem., Vol. 262, Issue 5, 2056-2061, 02, 1987
Phosphorylated fructose-1,6-bisphosphatase dephosphorylating protein phosphatase from Saccharomyces cerevisiae
D Horn and H Holzer
Phosphorylation of fructose-1,6-bisphosphatase with cyclic AMP- dependent
protein kinase from yeast is accompanied by a 50% decrease in the catalytic
activity (Pohlig, G. and Holzer, H. (1985) J. Biol. Chem. 260,
13818-13823). Using reactivation of phoshorylated fructose-1,6-
bisphosphatase as assay, a protein phosphatase was about 2,000-fold
purified to electrophoretic homogeneity from Saccharomyces cerevisiae. Upon
incubation with phosphorylated fructose-1,6-bisphosphatase the purified
protein phosphatase not only reverses the 50% inactivation caused by
phosphorylation, but also the previously observed change in the pH optimum
and in the ratio of activity with Mg2+ or Mn2+. The phosphatase is strongly
inhibited by heparin and fluoride. L-Carnitine, orthophosphate,
pyrophosphate, and succinate inhibit to 50% at concentrations from 1 to 10
mM. The molecular mass of the native phosphatase was found to be 180,000
Da. Sodium dodecyl sulfate-gel electrophoresis suggested four subunits with
a molecular mass of 45,000 Da each. Half-maximal activity was observed with
5 mM Mg2+ or Mn2+, the pH optimum of activity was found at pH 7. Using
polyclonal antibodies, disappearance of 32P-labeled
fructose-1,6-bisphosphatase and concomitant liberation of the expected
amount of inorganic [32P] phosphate was demonstrated.