The intrinsic structure of glucose transporter isoforms Glut1 and Glut3 regulates their differential distribution to detergent‐resistant membrane domains in nonpolarized mammalian cells

The hexose transporter family, which mediates facilitated uptake in mammalian cells, consists of more than 10 members containing 12 membrane‐spanning segments with a single N‐glycosylation site. We previously demonstrated that glucose transporter 1 is organized into a raft‐like detergent‐resistant membrane domain but that glucose transporter 3 distributes to fluid membrane domains in nonpolarized mammalian cells. In this study, we further examined the structural basis responsible for the distribution by using a series of chimeric constructs. Glucose transporter 1 and glucose transporter 3 with a FLAG‐tagged N‐terminus were expressed in detergent‐resistant membranes and non‐detergent‐resistant membranes of CHO‐K1 cells, respectively. Replacement of either the C‐terminal or N‐terminal cytosolic portion of FLAG‐tagged glucose transporter 1 and glucose transporter 3 did not affect the membrane distribution. However, a critical sorting signal may exist within the N‐terminal half of the isoforms without affecting transport activity and its inhibition by cytochalasin B. Further shortening of these regions altered the critical distribution, suggesting that a large proportion or several parts of the intrinsic structure, including the N‐terminus of each isoform, are involved in the regulation.