Glucose transport glycolysis

J. Chen, and J. Russo, Dysregulation of glucose transport, glycolysis, TCA cycle and glutaminolysis by oncogenes and tumor suppressors in eaneer cells. Biochim. Biophys. Acta., 1826 (2012)370-84. 

Before glycolysis from glucose can begin, glucose has to be transported into the ceU. This is achieved by a transporter protein, in the plasma membrane (Chapter 5). There are five different types of glucose transporter, all encoded by separate genes. The proteins have slightly different properties, different tissue distribution and somewhat different roles in these tissues. Their roles are briefly described in Table 6.1. A sixth transporter is specific for fructose it is... 

There are two biochemical situations in which to consider glucose transport and regulation of glycolysis ... 

Figure 6.14 An increase in the rate of glucose transport, in response to insulin, which increases the rate of glycolysis. This is achieved by increasing the concentrations of all the intermediates in the pathway, indicated by the arrows adjacent to the intermediates. Insulin, physical activity or a decrease in the ATP/ADP concentration ratio all result in increased rates of glucose transport in skeletal muscle. Insulin increases the rate about fivefold, physical activity about 50-fold.

Although the rate of glucose transport can regulate the flux through glycolysis, as indicated above, several enzymes also play a role. 

It increases the rate of glycolysis from glucose or glycogen (via activation of glycogen phosphorylase, glucose transport and phosphofructokinase (Chapter 6)). 

Fig. 8.1 Glucose metabolism in coupled neuron and astrocyte system. ATP is produced via oxidative energy metabolism (glycolysis, TCA cycle and oxidative phosphorylation) in neurons and in astrocytes. Na+ entry during electrical activity initiates increased oxidative energy metabolism within neurons. The activation of neuronal Na+-K+ ATPase in the plasma membrane leads to reduced levels of ATP, which rapidly activates glycolysis. This process requires an elevated glucose level, which is transported via the neuronal glucose transporter (GT). The generated ATP can restore the Na+/K+ balance via Na+-K+ ATPase. The rapid increase of glycolysis results in increased NADH/NAD+ and increased cytoplasmic pyruvate. In astrocytes,...

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