Structure-function relationship of glucose transporters catalyzing facilitated diffusion.

Abstract

Most mammalian cells depend on a continuous supply of glucose as the predominant source of ATP generation and substrate storage. The uptake of glucose into cells requires specific carrier proteins catalyzing the diffusion of the hexose along a concentration gradient which is maintained by the intracellular phosphorylation of the hexose. Molecular cloning of a protein (GLUT 1) mediating the uptake of glucose into erythrocytes (Mueckler et al., 1985), and the subsequent identification of homologous genes (GLUT2-4) revealed that a small family of genes is responsible for facilitated diffusion of the hexose into mammalian cells (Bell et al., 1990). It is now known that these genes belong to a subfamily of the large superfamily of transport facilitators which also comprises several yeast hexose transporters, plant hexose-proton symporters, and some bacterial sugar-proton symporters (Marger and Saier, 1993; Sauer and Tanner, 1993).