Which of the following enzymes are activated dephosphorylated state?
Covalent modification: Sho-term regulation is by covalent modification of the enzyme. Cyclic AMP-mediated cascade phosphorylates the enzyme which is inactive.Dephosphorylated form is active. Fuher, the activity of HMG CoA reductase is also regulated by the rate of degradation of enzyme protein. The synthetic and degradative pathways are reciprocally regulated to prevent futile cycles.ii. The phosphorylated form of glycogen phosphorylase is active, but glycogen synthase becomes inactive on phosphorylation.The covalently modified phosphorylase is active even without AMP. Active (dephosphorylated) glycogen synthase is responsive to the action of glucose-6- phosphate. Covalent modification modulates the effect of allosteric regulators. The hormonal control by covalent modification and allosteric regulation are interrelated.iii. These hormones act through a second messenger, cyclic AMP (cAMP)iv. The covalent modification of glycogen phosphorylase and synthase is by a cyclic AMP-mediated cascade. Specific protein kinases bring about phosphorylation and protein phosphatases cause dephosphorylation.Ref: DM Vasudevan, Page no: 149
HMG Co A reductase
Glycogen phosphorylase
Glycogen phosphorylase kinase
Citrate lyase
Enzymes