Glycogen synthesis and degradation

Function Location Connections Regulation ATP Yield ATP Cost Molecular Features 

To store glucose equivalents and retrieve them on demand 

Major deposits in liver for maintaining blood glucose Deposits in muscle for providing glucose for muscle energy requirements 

Glycogen to and from glucose 1-phosphate Glucose 1-phosphate to glucose 6-phosphate Glucose 6-phosphate to glucose (liver and kidney only) 

Glucose 6-phosphate to and from glycolysis and gluconeogenesis Glucose 6-phosphate to pentose phosphates (not reversible) 

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Regulation of glycogen synthesis and degradation is essentially the same in the liver and muscle, but there are a couple of wrinkles. Glycogen degradation is also activated in muscle in response to the rise in intracellular calcium levels that accompanies contraction. This is achieved by... 

Glycogen synthesis and degradation shown as a part of the essential reactions of energy metabolism (see Figure 8.2, p. 90, for a more detailed view of the overall reactions of metabolism). 

Regulation of glycogen synthesis and degradation in the well-fed state ... 

Fig. 1. Simultaneous operation of glycogen synthesis and degradation resulting in net hydrolysis of UTP.

Figure 5-10. Overview of glycogen synthesis and degradation. Solid arrows = glycogen synthesis broken arrows = glycogen degradation.

Figure 5-15. Hormonal regulation of glycogen synthesis and degradation. Solid lines indicate reactions that predominate when glucagon or epinephrine is elevated (steps 1 through 6 indicated by circled numbersy, dashed lines indicate those that predominate when insulin is elevated.

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