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Metabolic Compartmentation – A System Level Property of Muscle Cells
Laboratory of Bioenergetics, INSERM U884, Joseph Fourier University Grenoble, France
Laboratory of Bioenergetics, National Institute of Chemical and Biological Physics, Tallinn, Estonia
Institute of Cell Biology, ETH Zurich Hönggerberg, HPM D24, CH-8093 Zuerich, Switzerland
* Author to whom correspondence should be addressed.
Received: 15 April 2008; in revised form: 8 May 2008 / Accepted: 8 May 2008 / Published: 9 May 2008
Abstract: Problems of quantitative investigation of intracellular diffusion and compartmentation of metabolites are analyzed. Principal controversies in recently published analyses of these problems for the living cells are discussed. It is shown that the formal theoretical analysis of diffusion of metabolites based on Fick’s equation and using fixed diffusion coefficients for diluted homogenous aqueous solutions, but applied for biological systems in vivo without any comparison with experimental results, may lead to misleading conclusions, which are contradictory to most biological observations. However, if the same theoretical methods are used for analysis of actual experimental data, the apparent diffusion constants obtained are orders of magnitude lower than those in diluted aqueous solutions. Thus, it can be concluded that local restrictions of diffusion of metabolites in a cell are a system-level properties caused by complex structural organization of the cells, macromolecular crowding, cytoskeletal networks and organization of metabolic pathways into multienzyme complexes and metabolons. This results in microcompartmentation of metabolites, their channeling between enzymes and in modular organization of cellular metabolic networks. The perspectives of further studies of these complex intracellular interactions in the framework of Systems Biology are discussed.
Keywords: diffusion; metabolic (micro)compartmentation; cell structure; cytoskeleton; multienzyme complexes; channeling; regulation; Systems Biology.
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MDPI and ACS Style
Saks, V.; Beraud, N.; Wallimann, T. Metabolic Compartmentation – A System Level Property of Muscle Cells. Int. J. Mol. Sci. 2008, 9, 751-767.
Saks V, Beraud N, Wallimann T. Metabolic Compartmentation – A System Level Property of Muscle Cells. International Journal of Molecular Sciences. 2008; 9(5):751-767.
Saks, Valdur; Beraud, Nathalie; Wallimann, Theo. 2008. "Metabolic Compartmentation – A System Level Property of Muscle Cells." Int. J. Mol. Sci. 9, no. 5: 751-767.