| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Membrane Protein Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
* To whom correspondence should be addressed. E-mail: chris.cheeseman{at}ualberta.ca.
Facilitated glucose transporters (GLUT's) mediate transport of sugars across cell membranes using the chemical gradient of sugars as the driving force. Improved cloning techniques and database analyses have expanded this family of proteins to a total of 14 putative members. In this work a novel hexose transporter isoform, GLUT7, has been cloned from a human intestinal cDNA library using PCR-based strategy (GeneBank accession number AY571960). The encoded protein is comprised of 524 amino acid residues and shares 68% similarity and 53% identity with GLUT5, its most closely related isoform. When GLUT7 was expressed in Xenopus oocytes it showed high affinity transport for glucose (Km = 0.3mM) and fructose (IC50 = 0.060 mM). Galactose, 2 deoxyglucose and xylose were not transported. Uptake of 100µM D-glucose was not inhibited by 200µM phloretin or 100µM cytochalasin B. Northern blotting indicated that the mRNA for GLUT7 is present in the human small intestine, colon, testis and prostate. Western blotting and immunohistochemistry of rat tissues using an antibody raised against the predicted C-terminal sequence confirmed expression of the protein in the small intestine and indicated that the transporter is predominantly expressed in the enterocytes' brush-border membrane. The unusual substrate specificity and close sequence identity with GLUT5 suggest that GLUT7 represents an intermediate between class II GLUT's and the class I member GLUT2. Comparison between these proteins may provide key information as to the structural determinants for the recognition of fructose as a substrate.
This article has been cited by other articles:
|
|
 |
|
  V. Douard and R. P. Ferraris Regulation of the fructose transporter GLUT5 in health and disease Am J Physiol Endocrinol Metab, August 1, 2008; 295(2): E227 - E237. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Schurmann Insight into the "odd" hexose transporters GLUT3, GLUT5, and GLUT7 Am J Physiol Endocrinol Metab, August 1, 2008; 295(2): E225 - E226. [Full Text] [PDF]
|
|
|
|
|
|
C. Cheeseman GLUT7: a new intestinal facilitated hexose transporter Am J Physiol Endocrinol Metab, August 1, 2008; 295(2): E238 - E241. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. R. Manolescu, K. Witkowska, A. Kinnaird, T. Cessford, and C. Cheeseman Facilitated Hexose Transporters: New Perspectives on Form and Function Physiology, August 1, 2007; 22(4): 234 - 240. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F.-Q. Zhao and A. F. Keating Expression and Regulation of Glucose Transporters in the Bovine Mammary Gland J Dairy Sci, June 1, 2007; 90(13_suppl): E76 - E86. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. A. Stuart, M. E.A. Howell, and D. Yin Overexpression of GLUT5 in Diabetic Muscle Is Reversed by Pioglitazone Diabetes Care, April 1, 2007; 30(4): 925 - 931. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Stuart, D. Yin, M. E. A. Howell, R. J. Dykes, J. J. Laffan, and A. A. Ferrando Hexose transporter mRNAs for GLUT4, GLUT5, and GLUT12 predominate in human muscle Am J Physiol Endocrinol Metab, November 1, 2006; 291(5): E1067 - E1073. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X.-L. Cui, A. M. Schlesier, E. L. Fisher, C. Cerqueira, and R. P. Ferraris Fructose-induced increases in neonatal rat intestinal fructose transport involve the PI3-kinase/Akt signaling pathway Am J Physiol Gastrointest Liver Physiol, June 1, 2005; 288(6): G1310 - G1320. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
