POSTTRANSLATIONAL REGULATION OF NITRATE REDUCTASE-ACTIVITY - A ROLE FOR CA2-3-3-PROTEIN( AND 14)

The control of nitrate reductase (NR) activity by reversible protein p hosphorylation is a two-stage process: the enzyme is reversibly phosph orylated, and the phosphorylated form then binds an inhibitor protein. Recent results indicate that the phosphorylation reaction is Ca2+-dep endent and that the inhibitor is a member of the 14-3-3 family of prot eins. These results suggest the convergence of several signal transduc tion pathways in the control of nitrate assimilation. Recent results a lso implicate metabolites and 5'-AMP as possible effecters regulating the phosphorylation status of NR in vivo.