Transport, glucose

The main variation in the uptake is therefore taking place by varying the amount of active GLUT4 at the cell membrane [59-61, 82]. This is one of the important actions of insulin, but neural activity can also translocate GLUT4 independently of insulin [85]. This probably takes place during exercise [61, 82] and during stimulation from the portal sensor [44]. The glucose influx over the cell membrane can then be described like  

It is generally believed that GLUT transporters are symmetric [61], so they can transport both ways with the same affinity. Thus, the efflux is given by  

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The absorption of sulfonylureas from the upper gastrointestinal tract is faidy rapid and complete. The agents are transported in the blood as protein-bound complexes. As they are released from protein-binding sites, the free (unbound) form becomes available for diffusion into tissues and to sites of action. Specific receptors are present on pancreatic islet P-ceU surfaces which bind sulfonylureas with high affinity. Binding of sulfonylureas to these receptors appears to be coupled to an ATP-sensitive channel to stimulate insulin secretion. These agents may also potentiate insulin-stimulated glucose transport in adipose tissue and skeletal muscle. 

Transport proteins Elemoglobin Serum albumin Glucose transporter... 

Glucose Transport in Erythrocytes Occurs by Facilitated Diffusion... 

FIGURE 10.5 A model for the arrangement of the glucose transport protein in the erythrocyte membrane. Hydropathy analysis is consistent with 12 transmembrane helical segments. 

FIGURE 10.26 Glucose transport in E. coli is mediated by the PEP-dependent phosphotransferase system. Enzyme I is phosphorylated in the first step by PEP. Successive phosphoryl transfers to HPr and Enzyme III in Steps 2 and 3 are followed by transport and phosphorylation of glucose. Enzyme II is the sugar transport channel. 

Walmsley, A. R., 1988. The dynamics of die glucose transporter. Trends in Biochemical Sciences 13 226—231. 

Wheeler, T. J., and Hinkle, P, 1985. The glucose transporter of mammalian cells. Annual Review of Physiology 47 503-517. 

Gene activated Lipoprotein lipase fatty acid transporter protein adipocyte fatty acid binding protein acyl-CoA synthetase malic enzyme GLUT-4 glucose transporter phosphoenolpyruvate carboxykinase... 

Diabetes Mellitus Insulin Receptor Glucose Transporters ATP-dependent K+Channel PPARs... 

In addition to secretory cells, many non-secretory cells are capable of regulating exocytotic fusion of transport vesicles that are derived from endosomal precursors. For instance, vesicles enriched in plasma membrane transport proteins are incorporated in a regulated manner in order to alter metabolite fluxes. Examples include the glucose transporter GLUT-4 in muscle and fat tissues, a key element in the control of... 

Glucose transporters are integral membrane proteins that catalyze the permeation of sugars into cells, along or against a concentration gradient. 

Glucose transport activity is regulated through transcriptional and translational control of the GLUT proteins, through their activity, and through alterations of their intracellular distribution. Most importantly, the GLUT4 continuously cycles between an intracellular,... 

At present, the only available drug that stimulates glucose transport is insulin. Insulin increases the abundance of the GLUT4 in plasma membranes of adipose and muscle cells by its recruitment from intracellular storage sites (for a detailed description of its mechanism, see Chapter Diabetes Mellitus). 

Scheepers A, Joost HG, Schurmann A (2004) The glucose transporter families SGLT and GLUT molecular basis of normal and aberrant function. JPEN J Parenter Enteral Nub 28 364-371... 

Wood IS, Trayhurn P (2003) Glucose transporters (GLUT and SGLT) expanded families of sugar transport proteins. BrJNutr 89 3-9... 

GGM. Several missense mutations in human sodium-dependent glucose transporters (SGLT1) have been described that cause GGM. 

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

GLUT4 is a glucose transporter exclusively expressed in tissues with insulin-sensitive glucose uptake (heart, muscle, fat). Under basal conditions, GLUT4 is predominantly located in intracellular vesicles, and is... 

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