Family of glucose-transporter genes. Implications for glucose homeostasis and diabetes.
 Glucose transport by facilitated diffusion is mediated by a family of tissue-specific membrane glycoproteins.
 At least four members of this gene family have been identified by cDNA cloning.
 The HepG2-type transporter is the most widely distributed of these proteins.
 It provides many cells with their basal glucose requirement for ATP production and the biosynthesis of sugar-containing macromolecules.
 The liver-type transporter is expressed in tissues from which a net release of glucose can occur and in beta-cells of pancreatic islets.
 A genetic defect resulting in reduced activity of this transporter could hypothetically lead to the two principal features of non-insulin-dependent diabetes mellitus, insulin resistance and relative hypoinsulinemia.
 The adipocyte/muscle transporter is expressed exclusively in tissues that are insulin sensitive with respect to glucose uptake.
 This protein is an excellent candidate for a highly specific genetic defect predisposing to insulin resistance.
