Glycogen breakdown regulation

See also Mechanism of Activating Glycogen Breakdown, Kinase Cascade, Glycogen Breakdown Regulation, Phosphorolysis, Glycogen, Glucose- 1-Phosphate, cAMP... 

See also Phosphorolysis, Glycogen phosphorylase. Figure 13.18, Kinase Cascade, Figure 13.16, Figure 13.17, Polysaccharides, Glycogen Breakdown, Hydrolysis vs Phosphorolysis, Glycogen Breakdown Regulation... 

See also Reciprocal Regulation, Kinase Cascade (from chapter 13), Glycogen Breakdown Regulation,... 

Integration of regulation of glycogen synthesis and glycogen breakdown by glucose... 

The control of glycogen phosphorylase by the phosphorylation-dephosphorylation cycle was discovered in 1955 by Edmond Fischer and Edwin Krebs50 and was at first regarded as peculiar to glycogen breakdown. However, it is now abundantly clear that similar reactions control most aspects of metabolism.51 Phosphorylation of proteins is involved in control of carbohydrate, lipid, and amino acid metabolism in control of muscular contraction, regulation of photosynthesis in plants,52 transcription of genes,51 protein syntheses,53 and cell division and in mediating most effects of hormones. 

In addition to cAMP-mediated regulation, AMP and Ca2+ stimulate glycogen breakdown in muscle. 

Another type of regulation is accomplished by a series of proenzymes in which activation of the initial proenzyme by a biological signal activates the second proenzyme which, in turn, activates the third, and so on. Such an enzyme cascade process provides great amplification in terms of the amount of final product formed. Examples are blood coagulation, the dissolution of blood clots, complement activation, and glycogen breakdown. 

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