Binding to 14-3-3 proteins is not sufficient to inhibit nitrate reductase in spinach leaves

To assess the role of 14-3-3 proteins in the magnesium-dependent inhibition of nitrate reductase (NR),ve tested the effect of magnesium on NR binding to 14-3-3s by coimmunoprecipitation and gel filtration. The stability of th e 14-3-3 complex of NR was, unlike its activity, unaffected by magnesium, W e therefore conclude that binding to 14-3-3s per se does not inhibit NR. Ma gnesium inhibited 14-3-3-bound NR much more strongly than 14-3-3-free NR, 1 4-3-3s possibly reinforce NR inhibition by magnesium, (C) 2000 Federation o f European Biochemical Societies, Published by Elsevier Science B.V. All ri ghts reserved.