GLUT2 is a high affinity glucosamine transporter.
When expressed in Xenopus oocytes, GLUT1, 2 and 4 transport glucosamine with V(max) values that are three- to four-fold lower than for glucose. The K(m)s for glucosamine and glucose of GLUT1 and GLUT4 were similar. In contrast, GLUT2 had a much higher apparent affinity for glucosamine than for glucose (K(m)=0.8+/-0.1 mM vs. approximately 17-20 mM). Glucosamine transport by GLUT2 was confirmed in mammalian cells and, using hepatocytes from control or GLUT2-null mice, HgCl(2)-inhibitable glucosamine uptake by liver was shown to be exclusively through GLUT2. These data have implications for glucosamine effects on impaired glucose metabolism and for structure-function studies of transporter sugar binding sites.
Institute of Pharmacology and Toxicology, University of Lausanne, 27, rue du Bugnon, 1005 Lausanne, Switzerland.
Marc
M
Uldry
Mark
M
Ibberson
Masaya
M
Hosokawa
Bernard
B
Thorens
D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D005944:Glucosamine / Q000378:metabolism*; D051273:Glucose Transporter Type 2; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes; D014162:Transfection; D014981:Xenopus
D051273:Glucose Transporter Type 2; D009004:Monosaccharide Transport Proteins; D005944:Glucosamine