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.
Sakyo
Tomoko
T
Pharmaceutical Research Center, School of Pharmacy, Iwate Medical University, Morioka, Iwate 028-3694, Japan.
Naraba
Hiroaki
H
Teraoka
Hirobumi
H
Kitagawa
Takayuki
T
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000737:chemistry* / Q000378:metabolism*; D051274:Glucose Transporter Type 3 / Q000737:chemistry* / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000737:chemistry; D021962:Membrane Microdomains / Q000378:metabolism*; D009842:Oligopeptides; D010455:Peptides / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D009842:Oligopeptides; D010455:Peptides; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C085706:FLAG peptide; D005947:Glucose