Reactivation of the phospho form of the NAD-dependent glutamate dehydrogenase by a yeast protein phosphatase.

A protein phosphatase was isolated from the yeast, Candida utilis, which could reactivate (dephosphorylate) the phosphorylated form of the NAD-dependent glutamate dehydrogenase. The protein could also dephosphorylate casein, histone and kemptide (a heptapeptide corresponding to the phosphorylation site of liver pyruvate kinase). Reactivation of the phosphorylated glutamate dehydrogenase was stimulated by the simultaneous addition of NAD and L-glutamate; 2-oxoglutarate, NH+4 and NADH had no effect. The reactivation of phosphorylated glutamate dehydrogenase could be inhibited by phosphate, pyrophosphate and fluoride.