BACKGROUND A group of related glucose transporters (Glut1-5 and 7) mediate the facilitated diffusion of glucose in nonepithelial mammalian tissues. Within insulin-responsive tissues such as muscle and fat, Glut1 contributes to basal glucose uptake while Glut4 is responsible for insulin stimulated glucose transport (1-3). Glut4 is a 12-transmembrane domain protein that facilitates glucose transport in the direction of the glucose gradient. This transporter localizes to intracellular organelles (endosomes) in unstimulated cells and translocates to the cell surface following insulin stimulation (1, 2, 4). Translocation of Glut4 is dependent on Akt, which may act by phosphorylating AS160, a RabGAP protein involved in membrane trafficking (5).
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2. Slot, J.W. et al. (1991) Proc. Natl. Acad. Sci. USA 88, 7815–7819.
3. James, D.E. et al. (1989) Nature 338, 83–87.
4. Barrett, M.P. et al. (1999) Curr. Opin. Cell Biol. 11, 496–502.
5. Zeigerer, A. et al. (2004) Mol. Biol. Cell 15, 4406–4415.
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