@article{bachmann_huber_athwal_wu_ferl_huber_1996, title={14-3-3 proteins associate with the regulatory phosphorylation site of spinach leaf nitrate reductase in an isoform-specific manner and reduce dephosphorylation of Ser-543 by endogenous protein phosphatases}, volume={398}, ISSN={["0014-5793"]}, DOI={10.1016/S0014-5793(96)01188-X}, abstractNote={Three lines of evidence indicate that the 14‐3‐3 proteins that inactivate the phosphorylated form of spinach leaf NADH:nitrate reductase (NR) bind to the enzyme at the regulatory phosphorylation site (Ser‐543). First, a phosphorylated synthetic peptide based on the regulatory site can prevent and also reverse the inactivation of phospho‐NR caused by 14‐3‐3 proteins. Second, sequence‐specific and phosphorylation‐dependent binding of the aforementioned synthetic peptide to the 14‐3‐3 proteins was demonstrated in vitro. Third, 14‐3‐3 proteins were required for the ATP‐dependent phosphorylation of NR (as assessed by activity measurements) in the presence of NR‐kinase and leaf protein phosphatases. Lastly, we demonstrate specificity of recombinant Arabidopsis 14‐3‐3 isoforms in the interaction with phospho‐NR: ω > χ > ν ⋙ gf, ψ.}, number={1}, journal={FEBS LETTERS}, author={Bachmann, M and Huber, JL and Athwal, GS and Wu, K and Ferl, RJ and Huber, SC}, year={1996}, month={Nov}, pages={26–30} }
 @article{bachmann_shiraishi_campbell_yoo_harmon_huber_1996, title={Identification of Ser-543 as the major regulatory phosphorylation site in spinach leaf nitrate reductase}, volume={8}, DOI={10.2307/3870328}, number={3}, journal={Plant Cell}, author={Bachmann, M. and Shiraishi, N. and Campbell, W. H. and Yoo, B.-C. and Harmon, A. C. and Huber, S. C.}, year={1996}, pages={505} }
 @article{bachmann_mcmichael_huber_kaiser_huber_1995, title={PARTIAL-PURIFICATION AND CHARACTERIZATION OF A CALCIUM-DEPENDENT PROTEIN-KINASE AND AN INHIBITOR PROTEIN REQUIRED FOR INACTIVATION OF SPINACH LEAF NITRATE REDUCTASE}, volume={108}, ISSN={["0032-0889"]}, DOI={10.1104/pp.108.3.1083}, abstractNote={Evidence is accumulating that the activity of spinach (Spinacia oleracea L.) leaf NADH:nitrate reductase (NR) is modulated both in vitro and in vivo by protein phosphorylation. From the present study we report the partial purification of the two protein factors needed for NR inactivation. We identified NR-protein kinase (NR-PK) as a calcium-dependent and metabolite-regulated protein kinase and have provided additional evidence that phosphorylation of NR is necessary but not sufficient to inactivate the enzyme. The inhibitor protein required for inactivation of phospho-NR was purified 625-fold by polyethylene glycol fractionation and sequential column chromatography. Using partially purified inhibitor protein and NR-PK, we characterized NR inactivation (increased sensitivity to Mg2+ inhibition) in a reconstituted in vitro system. NR-PK activity was inhibited by a variety of metabolic phosphate esters including di-hydroxyacetone phosphate, glucose-6-phosphate, and fructose-1,6-bisphosphate. Light-to-dark transition experiments with a starchless tobacco (Nicotiana sylvestris) mutant, which accumulates phosphate esters during the photoperiod, indicated that NR inactivation in vivo might, indeed, be down-regulated by metabolites. Additionally, we postulate that cytosolic free calcium could play an important role in the regulation of NR activity in vivo.}, number={3}, journal={PLANT PHYSIOLOGY}, author={BACHMANN, M and MCMICHAEL, RW and HUBER, JL and KAISER, WM and HUBER, SC}, year={1995}, month={Jul}, pages={1083–1091} }