Different mammalian facilitative glucose transporters expressed in Xenopus oocytes

Xenopus oocytes exhibit an extremely low basal glucose transport and are thus ideally suited for the expression of heterologous glucose transporters. They have, therefore, proven to be a very valuable expression system to functionally express the erythrocyte/brain (GLUT1), the liver (GLUT2), and the adipocyte/muscle (GLUT4) glucose transporters. Characterization of their functional properties indicates that they fulfill the criteria of a glucose transport protein by demonstrating saturation kinetics, stereospecificity, and inhibition by cytochalasin B. Although mammalian facilitative glucose transporters have been expressed in bacteria and eukaryotic cell lines, the present data emphasize the advantage of using Xenopus oocytes for comparative kinetic analysis of the various members of the facilitated diffusion glucose transporter gene family.