Calmidazolium Calmodulin

As in the case of the dikinase regulatory cascade (see Fig. 1), little is known with certainty with respect to how light modulates the phosphorylation-status (activation-state) of cytoplasmic PEPC other than it, too, is dependent, either directly or indirectly, on photosynthetic electron transport and/or photophosphorylation (19, 20). Neither dithiothreitol-reduced spinach leaf thioredoxin h [Td (30)], PPi, fructose 2,6-bisphosphate (Fru 2,6-P2), various combinations of EGTA/calcium/calmodulin (CaM) [see Table 1 (Refs. 29, 31)] nor the CaM-antagonist calmidazolium (R. Chollet and J. Vidal, unpublished) has any significant effect on the regulatory phosphorylation and/or activation of purified dark-form PEPC in our reconstituted in vitro system. A one-hour preincubation of the dark-form PK with Mg-ATP is also without effect on its subsequent activation of PEPC. Thus, we currently have no supportive evidence... 

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