Glucose Transport Facilitators

GLUT stands for Glucose Transport Facilitators. Glucose Transporters... 

Schurmann, A., et al. The glucose transport facilitator GLUT8 is predominantly associated with the acrosomal region of mature spermatozoa. Cell Tissue Res. 2002,... 

Boccia MM, Kopf SR, Baratti CM (1999) Phlorizin, a competitive inhibitor of glucose transport, facilitates memory storage in mice. Neurobiol Learn Mem 71 104... 

Glucose Transport in Erythrocytes Occurs by Facilitated Diffusion... 

GLUT2 is a glucose/fructose transport facilitator expressed in liver, small intestine, kidney, and pancreatic p-cells. GLUT2 has low-affinity for glucose (Km= 60 mM) and fructose (ivm=65 mM), and is an essential part of the glucose sensor of pancreatic (3-cells which controls insulin secretion and biosynthesis. 

The entry rate of glucose into red blood cells is far greater than would be calculated for simple diffusion. Rather, it is an example of facilitated diffiision (Chapter 41). The specific protein involved in this process is called the glucose transporter or glucose permease. Some of its properties are summarized in Table 52-3-The process of entry of glucose into red blood cells is of major importance because it is the major fuel supply for these cells. About seven different but related glucose transporters have been isolated from various tissues unlike the red cell transporter, some of these are insidin-dependent (eg, in muscle and adipose tissue). There is considerable interest in the latter types of transporter because defects in their recruitment from intracellular sites to the surface of skeletal muscle cells may help explain the insulin resistance displayed by patients with type 2 diabetes mellitus. 

By far the most complete study of the kinetics of mammalian passive glucose transporters has been done on the GLUT-1 isoform in the human erythrocyte. The transport of glucose in this cell type is a classic example of facilitated diffusion, the... 

Doege, H., et al. Activity and genomic organization of human glucose transporter 9 (GLUT9), a novel member of the family of sugar-transport facilitators predominantly expressed in brain and leucocytes. Biochem. J. 2000, 350, 771-776. 

Phay, J. E., H. B. Hussain, and J. F. Moley. Cloning and expression analysis of a novel member of the facilitative glucose transporter family, SLC2A9 (GLUT9). Genomics 2000, 66, 217-220. 

Doege, H., et al. GLUT8, a novel member of the sugar transport facilitator family with glucose transport... 

Olson, A. L. and J. E. Pessin. Structure, function, and regulation of the mammalian facilitative glucose transporter gene family. Annu. Rev. Nutr. 1996, 36, 235-256. 

Hruz, P. W. and M. M. Mueckler. Structural analysis of the GLUT1 facilitative glucose transporter. Mol. Membr. Biol. 2001, 38, 183-193. 

Immunohistochemical study ND not determined GLUT1 facilitative glucose transporter MCT1 monocarboxylate transporter CRT creatine transporter LAT1 L-type amino acid transporter TAUT taurine transporter ENT equilibrative nucleoside transporter Oatp organic anion-transporting polypeptide PAH p-aminohippuric acid RUI retinal uptake index TR-iBRB rat retinal capillary endothelial cells. 

Glucose transporters in muscle and fat tissue operate by facilitated diffusion. 

Figure 4-6. Mechanism of facilitated diffusion mediated by a glucose transporter. This is an example of uniport. The reversible interconversion between conformations of the transporter in which the glucosebinding site is alternately exposed to the exterior and interior of the cell is called a ping-pong mechanism.

---