title: Characterization of GLUT5 domains responsible for fructose transport.
abstract: The domains responsible for the fructose specificity of GLUT5 were investigated by creating chimeras of GLUT5 with the selective glucose transporter GLUT3, which were expressed in Xenopus oocytes. 3-O-Methylglucose uptake of chimeric GLUT3-5 (M11; GLUT3 to the 11th transmembrane domain, GLUT5 to the carboxyl end) was similar to that of GLUT3, while fructose was not transported. Fructose uptake of chimeric GLUT5-3 (M3-5) to -5 (GLUT3 from the 3rd to 5th transmembrane domains, the rest GLUT5) was similar to that of GLUT5; no glucose was transported. Four chimeras transported neither fructose nor glucose: GLUT3-5 (M5; GLUT3 to the 5th transmembrane domain, GLUT5 to the carboxyl end), GLUT5-3 (M2; GLUT5 to the 2nd transmembrane domain, the rest GLUT3), GLUT5-3 (M3-11) to -5 (GLUT3 between the 3rd and 11th transmembrane domains, the rest GLUT5) and GLUT5-3 (M3-5) to -5-3 (M11; GLUT3 from the 3rd to 5th transmembrane domains and after the 11th transmembrane domain, the rest GLUT5). They, nevertheless, induced full-size proteins that were transported to the cell surface, as demonstrated by exofacial labeling with biotin. To conclude, the GLUT5 domain from the amino-terminus to the third transmembrane domain and that between the 5th and 11th transmembrane stretches seem to be necessary for fructose uptake.
authors.affiliation: Department of Endocrinology and Metabolism, Hebrew University Hadassah Medical Center, Jerusalem, Israel. buchs@hadassah.org.il
authors.forename: A E
authors.initials: AE
authors.lastname: Buchs
authors.forename: S
authors.initials: S
authors.lastname: Sasson
authors.forename: H G
authors.initials: HG
authors.lastname: Joost
authors.forename: E
authors.initials: E
authors.lastname: Cerasi
mesh_terms: D000818:Animals; D001692:Biological Transport; D005260:Female; D005632:Fructose / Q000378:metabolism*; D051296:Glucose Transporter Type 5; D009004:Monosaccharide Transport Proteins / Q000737:chemistry* / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
chemical_list: D051296:Glucose Transporter Type 5; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; D005632:Fructose