HETEROGENEOUS DISTRIBUTION AND ORGANIZATION OF CYTOSKELETAL PROTEINS DRIVE DIFFERENTIAL MODULATION OF METABOLIC FLUXES

On the basis of experimental data obtained in vitro, we propose that d ifferential segregation of actin and tubulin in the cytoplasm may be a regulatory mechanism of metabolic fluxes. The results presented point out that the same enzymes may be differentially modulated at differen t locations in the cytoplasm, depending on the cytoskeletal protein pr esent at that location, its concentration, polymeric status, or geomet ric arrangement. Essentially, actin or microtubular protein would exer t their effect on enzymatic catalysis through displacement of the equi librium of enzyme oligomers either to active or less active species. T he latter was corroborated by mathematical modeling of the dynamic cou pling between microtubular protein assembly-disassembly and pyruvate k inase activity. From these results, a precise biochemical meaning can be given to the putative linkage existing between the mechanisms by wh ich cells rearrange their cytoplasmic architecture and the dynamics of biochemical reactions taking place concomitantly. (C) 1996 Wiley-Liss , Inc.