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The mechanism of activation of heart fructose 6-phosphate,2-kinase:fructose-2,6-bisphosphatase.

1987; Elsevier BV; Volume: 262; Issue: 2 Linguagem: Inglês

10.1016/s0021-9258(19)75838-4

1083-351X

Kazuo Kitamura, Kosaku Uyeda,

Diet, Metabolism, and Disease

Partially purified fructose-6-P,2-kinase:fructose-2.6-bisphosphatase from beef heart was phosphorylated by CAMP protein kinase.The phosphorylated fructose-6-P,2-kinaseshows lower K,,, for Fru-6-P (43 versus 105 PM) and for ATP (0.55 versua 1.3 mM) but no change in the V,,, compared to those for unphosphorylated enzyme.There was no detectable change in K,,, or V, , of fructose-2,6-bisphosphatase activity by the phosphorylation.These changes in heart fructose-6-P,2-kinase were in direct contrast to previous results for the liver isozyme in which phosphorylation led to inhibition of the kinase activity and activation of the phosphatase activity.