GLUT1 was the first glucose transporter to be characterized. It is widely distributed in fetal tissues. In the adult it is expressed at highest levels in erythrocytes and also in the endothelial cells of barrier tissues such as the blood-brain barrier. Glut1 is a major receptor for take-up of Vitamin C as well as glucose, especially in non vitamin C producing mammals as part of an adaptation to compensate by participating in a Vitamin C recycling process. In mammals that do produce Vitamin C Glut4 is often expressed instead of Glut1.
GLUT1 behaves as a Michaelis-Menten
enzyme and contains 12 membrane-spanning alpha helices
, each containing 20 amino acid residues. A helical wheel analysis shows that the membrane spanning alpha helices are amphipathic
, with one side being polar and the other side hydrophobic. Six of these membrane spanning helices are believed to bind together in the membrane to create a polar channel in the center through which glucose can traverse, with the hydrophobic regions on the outside of the channel adjacent to the fatty acid tails of the membrane.
Mutations in the GLUT1 gene are responsible for GLUT1 deficiency or De Vivo disease
, which is a rare autosomal dominant disorder. This disease is characterized by a low cerebrospinal fluid
glucose concentration (hypoglycorrhachia) which results from impaired glucose transport across the blood-brain barrier.
Role in HTLV infection
GLUT1 is also a receptor used by the HTLV
virus to gain entry into target cells.