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GLUT2 is a high affinity glucosamine transporter.
Marc Uldry1, Mark Ibberson, Masaya Hosokawa
1Institute of Pharmacology and Toxicology, University of Lausanne, 27, rue du Bugnon, 1005 Lausanne, Switzerland.
FEBS Letters
|July 24, 2002
Summary
Glucose transporter 2 (GLUT2) exhibits a higher affinity for glucosamine than glucose. This finding is crucial for understanding glucosamine
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Glucose transporters (GLUTs) are critical for cellular glucose uptake.
- Glucosamine is a glucose analog with potential therapeutic applications.
- Understanding the substrate specificity of GLUTs is essential for metabolic research.
Purpose of the Study:
- To investigate the transport kinetics of glucosamine by GLUT1, GLUT2, and GLUT4.
- To determine the role of GLUT2 in hepatic glucosamine uptake.
- To explore the implications of glucosamine transport for glucose metabolism and transporter structure-function relationships.
Main Methods:
- Expression of GLUT1, GLUT2, and GLUT4 in Xenopus oocytes.
- Measurement of glucosamine and glucose transport kinetics (Km and Vmax).
- Confirmation of GLUT2-mediated glucosamine transport in mammalian cells.
- Analysis of glucosamine uptake in hepatocytes from wild-type and GLUT2-null mice.
Main Results:
- GLUT1 and GLUT4 transported glucosamine at lower Vmax values compared to glucose, with similar Km values.
- GLUT2 displayed a significantly higher apparent affinity for glucosamine (lower Km) than for glucose.
- Glucosamine uptake in mammalian cells was mediated by GLUT2.
- Hepatic glucosamine uptake in mice was exclusively dependent on GLUT2, as shown by studies with GLUT2-null mice.
Conclusions:
- GLUT2 exhibits distinct substrate specificity, favoring glucosamine over glucose.
- GLUT2 plays a primary role in hepatic glucosamine uptake.
- These findings have implications for understanding glucosamine's effects on glucose metabolism and for studying GLUT transporter binding sites.