GLUT1

GLUT's are family of proteins which aim to transport glucose using its downhill gradient across membranes. There are many different GLUT's, however, each has a significantly different role in the transport of molecules. ^[1] For example, GLUT1 is a type of glucose transporter found in the cell membrane of erythrocyte and brain cells and is encoded by the gene SLC2A ^[2]. The GLUT family of glucose transporters are an example of uniporters, meaning that the carrier protein transports one substrate. Whereas, GLUT 5, for example, is used more often to transport fructose across membranes. ^[3]

GLUT 1 is the name of the GLUT transporter on the plasma membrane of erythrocytes ^[4]. It's presence allow glucose to enter the cell 50,000 times faster than by normal diffusion^[5]. The protein consists of 12 hydrophobic transbembrane segments ^[6]. GLUT 1 has two different conformational states which allow it to transport glucose across the membrane^[7] When the substrate (glucose) binds to the protein in its T₁ state (binding site exposed to the outside of the cell) a conformational change is induced in the protein, it shifts to the T2 conformational state, allowing it to release glucose into the cell^[8]. This can occur in reverse when extracellular glucose levels are lower than intracellular levels. 

References

1. ↑ Berg.J.M, Stryer.L, Tymoczko J.L, Biochemistry, seventh edition, WH Freeman, 2012 page 493
2. ↑ Leszek Szablewski, 2011, Glucose Homeostasis and Insulin resistance (e-book), Bentham Science Publisher, Available through:
3. ↑ Berg.J.M, Stryer.L, Tymoczko J.L, Biochemistry, seventh edition, WH Freeman, 2012 page 493
4. ↑ Becker W, Kleinsmith L, Hardin J (2004). The World of the Cell, 6th edition, p201. San Francisco: Pearson Education.
5. ↑ Becker W, Kleinsmith L, Hardin J (2004). The World of the Cell, 6th edition, p201. San Francisco: Pearson Education.
6. ↑ Becker W, Kleinsmith L, Hardin J (2004). The World of the Cell, 6th edition, p201. San Francisco: Pearson Education.
7. ↑ Becker W, Kleinsmith L, Hardin J (2004). The World of the Cell, 6th edition, p202. San Francisco: Pearson Education.
8. ↑ Becker W, Kleinsmith L, Hardin J (2004). The World of the Cell, 6th edition, p202. San Francisco: Pearson Education.