Glucose transport system

Mizuma, T., et al. Intestinal active absorption of sugar-conjugated compounds by glucose transport system implication of improvement of poorly absorbable drugs. Biochem. Pharmacol. 1992, 43, 2037-2039. 

Historically important as an example of flux coupling, and one that was investigated in detail becoming a paradigm for coupled transport, was the sodium coupled glucose transport system of the small intestine and kidney (see below). This was a symport (or co-transport) rather than an antiport, normally carrying glucose into the cell coupled to a flow of sodium ions in the same direction. 

McCormick, J.I., Tsang, D Johnstone, R.M. (1984). A simple and efficient method for reconstitution of amino acid and glucose transport systems from Ehrlich ascites cells. Arch. Biochem. Biophys. 231,355-365. 

A group of receptors exists that responds to so-called growth factors such as insulin, epidermal growth factor, platelet-derived growth factor, etc. These receptors have an extracellular domain that binds the growth factor and an intracellular domain that possesses latent kinase activity. The interaction of insulin, for example, results in autophosphorylation of the intracellular domain and subsequent internalization of the insulin-receptor complex. The internalized complex now possesses the properties of a tyrosine kinase and can phosphorylate cell substrates that produce the appropriate intracellular effect. However, these kinases differ from the usual protein kinases in that they phosphorylate proteins exclusively on tyrosine hydroxyl residues. The ensemble of proteins phosphorylated by the insulin receptor has not yet been identified, but there is supportive evidence that tyrosine kinase activity is required for the major actions of insulin. For example, it is possible that a membrane-linked glucose transport system becomes activated following insulin-stimulated phosphorylation. 

R, Kinne, Properties of the glucose transport system in the reiud brush border membrane, Curr. Top. Mem. Trans., 8 209-267 (1976),... 

The transport of glucose by the small intestine is also sodium dependent, but glucose transport systems also exist that are not sodium dependent. The concept that the passage of any nutrient through a cell membrane depends on sodium is discussed in more detail in Chapter 10. 

Traxinger, R, R., and Marshall, S. (1989). Role of amino acids in modulating glucose-induced desensItiz.ation of the glucose transport system. /. BieJ. Chem. 264, 20910-20916. 

Kamieli, E., Zamowski, M. J., Hissin, P. J., Simpson, L. A., Salans, L. B., and Cushman, S. W. (1981). Insulin-stimulated translocation of glucose transport systems in isolated rat adipose cell. /. Biol. Chem. 256, 4772-4777. 

Table 5-1. Effect of Insulin on Glucose Transport Systems of Various Tissues...

A classic cell model widely used to study the signal flow from the receptor to the glucose-transport system is the isolated adipocyte where activation and... 

GLUT 1 Human erythrocyte Blood-brain barrier Blood-retinal barrier Blood-placental barrier Blood-testis barrier Expressed in cell types with barrier functions a high-affinity glucose transport system... 

Galperin, M.Y., Noll, K.M., and Romano, A.H. (1996) Xhe glucose transport system of the hyperthermophilic anaerobic bacterium... 

The properties of the glucose transport system may be summarized as follows. The process involves combination of the sugar with a stereospecific site on the membrane and is distinct from diffusion. The process is reversible, and free sugar is liberated on either side of the membrane. Transport... 

DiMarco AA, Romano AH. (1985). D-Glucose transport system of Zymomonas mobilis. Appl Environ Microbiol, 49, 151-157. 

Busturia, a. and R. Lagunas. 1986. Catabolite inactivation of the glucose transport system in Saccharomyces cerevisiae. J. Gen. Microbiol. 132 379-385. 

Figure 9.2 Glucose transport system and carbon catabolite repression reiated with giucose-specific phosphotransferase system in Escherichia coli. MgIBAC the gaiactose ABC transporter GaiP the galactose H+ symporter CRP the cAMP receptor protein PEP phosphoenoipyruvate.

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