title: Characterization of rat GLUT5 and functional analysis of chimeric proteins of GLUT1 glucose transporter and GLUT5 fructose transporter.
abstract: To investigate the biological and biochemical properties of GLUT5, rat GLUT5 complementary DNA was transfected into Chinese hamster ovary cells. Rat GLUT5 was exclusively targeted to the plasma membrane and exhibited a transport activity, not for glucose, but for fructose. The affinity for fructose (Km = 11.6mM) was much higher than that of GLUT2, the other glucose transporter with fructose transport activity. Interestingly, rat GLUT5 was not photolabeled with 0.5 microM cytochalasin B, whereas a similar amount of GLUT1 was adequately photolabeled under the same experimental conditions. Next, to investigate the domains required for transport of glucose/fructose in GLUT1 and/or GLUT5, several chimeric GLUT1/GLUT5 proteins were expressed, and their glucose and/or fructose transport activities were studied. The intracellular middle loop and the region encompassing the membrane spanning domains 7-12 were observed to have crucial roles in GLUT1 glucose transport, whereas replacement of the N-terminal half or the intracellular C-terminal region with the corresponding region of GLUT5 produced no marked effects on glucose transport activity. In contrast, both the N-terminal half encompassing the region from the N-terminus through the 6th membrane spanning domain and the intracellular C-terminal region were mandatory for GLUT5 fructose transport. In conclusion, GLUT5 is a transporter exclusively for fructose and the structural requirements for fructose transport are more stringent than those for glucose transport among hexose transporter proteins.
authors.affiliation: Institute for Adult Disease, Asahi Life Foundation, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Inukai
authors.forename: H
authors.initials: H
authors.lastname: Katagiri
authors.forename: K
authors.initials: K
authors.lastname: Takata
authors.forename: T
authors.initials: T
authors.lastname: Asano
authors.forename: M
authors.initials: M
authors.lastname: Anai
authors.forename: H
authors.initials: H
authors.lastname: Ishihara
authors.forename: M
authors.initials: M
authors.lastname: Nakazaki
authors.forename: M
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Yazaki
authors.forename: Y
authors.initials: Y
authors.lastname: Oka
mesh_terms: D000345:Affinity Labels; D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002462:Cell Membrane; D006224:Cricetinae; D003571:Cytochalasin B; D018076:DNA, Complementary / Q000235:genetics; D005455:Fluorescent Antibody Technique; D005632:Fructose / Q000378:metabolism; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D051296:Glucose Transporter Type 5; D007700:Kinetics; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010777:Photochemistry; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D000345:Affinity Labels; D018076:DNA, Complementary; D051272:Glucose Transporter Type 1; D051296:Glucose Transporter Type 5; D009004:Monosaccharide Transport Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C495679:Slc2a1 protein, rat; D005632:Fructose; D003571:Cytochalasin B; D005947:Glucose