Spatio-temporal regulation of glycosis and oxidative phosphorylation in vivo
The aim of this chapter is to present some recent advances in the in vivo control and regulation of glycolysis and oxidative phosphorylation with special emphasis on yeast and tumour cells. These insights are analysed in the conceptual framework of dynamic organization in living cellular systems, focusing on the interaction (coupling) between two major catabolic processes occurring in two different cellular compartments. Old and new experimental data are revised in the light of powerful new technologies (e.g. NMR, confocal microscopy) and quantitative techniques combined with mathematical modelling. They are described under the general topic of dynamic organization which emerges from multiple interactions between compartments and processes inside cells. Those compartments may be of structural origin – for example, plasma membrane delineating the cell’s boundaries, or mitochondrial/ cytoplasmic membranes – or functional ones such as the alternating association–dissociation of enzymes to subcellular structures (e.g. mitochondria, cytoskeleton) with different kinetic properties in each state. Two novel regulatory mechanisms at the level of the cytoskeleton may add a new dimension to the in vivo physiological properties of cells. One of these mechanisms concerns the regulation of metabolic fluxes by polymerization–depolymerization of microtubular protein in a concentration dependent manner. The other implies the differential regulation of enzymatic fluxes sustained by the heterogeneous distribution of the major cytoskeleton constituents (actin and microtubular protein). The consequences of the fractal organization of the cytoplasm as a percolation cluster on enzyme catalysis are explored. One main suggestion prompted by the modulatory power of the polymeric status and concentration of cytoskeleton components is that it could function as an intracellular mechanism of synchronization between microscopic (local) and macroscopic (global) processes.
KeywordsOxidative Phosphorylation Percolation Threshold Metabolic Flux Glycolytic Enzyme Glycolytic Flux
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