Fig. 1.

Fluxes affecting steady-state cytosolic glucose concentrations in plant cells. Glucose and its activated derivates can be imported into the cytosol, and stored in the vacuole or plastids. They then serve as precursors for the biosynthesis of primary and secondary metabolites as well as cell wall biosynthesis, or they can be used to produce energy. Cells control the individual fluxes depending on the developmental stage and the environmental conditions. (a) Degradation of storage compounds and import are used to allow rapid biosynthesis; (b) fluxes favor storage and export. A key question is thus: how are the individual fluxes controlled?