Glucose physiological roles

Glucose entry into most cells is concentration driven and independent of sodium. Four glucose transporters (GLUT) are listed in Table 1-12-1. They have different afiinities for glucose coinciding with their respective physiologic roles. Normal glucose concentration in peripheral blood is 4-8 mM (70-140 m dL). 

The recent discovery of the dual nature of the enzyme, involving potent synthetic as well as hydrolytic activities, has served as a basis for a variety of new control mechanisms and physiological roles for the catalyst. For example, hydrolytic activity of the enzyme is limited through competitive inhibition by PPi, carbamyl-P, Pi HC03 , ATP, ADP, and various other phosphoanhydrides. Glucose itself, through participation as phosphoryl acceptor alternative with water (30, 31, Jfl), may regulate its own release in an autocatalytic manner (9, 10, 169). 

Skeletal muscle uncoupling by ectopic expression of mitochondrial UCP-1 has been shown to result in a lean phenotype in mice characterized by increased EE, resistance to diet-induced obesity, and improved glucose tolerance. UCP-2 is a member of the mitochondrial transporter superfamily that uncouple proton entry in the mitochondrial matrix from ATP synthesis. Although its physiological role remains to be established, UCP-2 is considered a candidate gene for association with energy metabolism and obesity. It is worth noting that the possible association of... 

The structure of glucose is found in Sectmn 17.4. The physiological roles of glucose are discussed in Chapters 21 and 23. 

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