Glucose transporter

The glucose transporters of the GLUT family of mammals belong to the family of passive glucose facilitators. So far, 11 membrane proteins could be assigned to the GLUT family (molecular weight: 45-55 kDa). They are characterized by a tissue- and cell-specific distribution and by certain kinetic and regulatory properties. GLUT5 is mainly found in the small intestine and is responsible for the transport of fructose (see below fructose intolerance).

• GLUT1: mainly in erythrocytes and brain; placenta (basal glucose supply for growing/dividing cells; transport across blood-tissue barriers).
• GLUT2: liver, pancreatic β cells, kidney, small intestine (intestinal and renal absorption; pancreatic and hepatic control of glucose homeostasis).
• GLUT3: neurons of the brain (absorption from cerebrospinal fluid in parenchymal cells of the brain).
• GLUT4: skeletal and cardiac muscle cells, adipocytes (glucose transport in cells of insulin-sensitive tissues).
• GLUT5: Small intestine (transport of fructose; see below fructose intolerance).
• GLUT6: Brain, peripheral leucocytes (previously unknown function).
• GLUT7: hepatocytes (release of glucose from the liver into the bloodstream).
• GLUT8: testicular tissue; small amounts in the small intestine, skeletal muscles and brain (glucose supply for DNA synthesis in sperm; possibly hormonally regulated).
• GLUT9: Liver, kidney (so far unknown function).
• GLUT10: liver, pancreas (function unknown so far).
• GLUT11: heart and skeletal muscles (unknown function).

1. Mueckler M (1994) Faciliative glucose transporters. Eur J Biochem 219: 713-725
2. Velten FW, Bayrl C (2007) Fructose malabsorption - the other side of health-conscious nutrition. Act Dermatol 33: 373-378