Which of the following is TRUE about the liver enzymes which are responsible for dephosphorylation and phosphorylation?
At the same time as phosphorylase is activated by a rise in concentration of cAMP ( phosphorylase kinase), glycogen synthase is conveed to the inactive form; both effects are mediated cAMP-dependent protein kinase. Phosphorylation is increased in response to cAMP formed from ATP by adenylyl cyclase in response to hormones such as epinephrine, norepinephrine, and glucagon. Phosphorylation of glycogen phosphorylase increases its activity; phosphorylation of glycogen synthase reduces its activity. Ref: Bender D.A., Mayes P.A. (2011). Chapter 19. Metabolism of Glycogen. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.
Phosphorylase is always activated by cAMP dependent Protein kinase
Always activates the enzyme
Catecholamines does not have any role in this process
Phosphorylation of glycogen synthase increases its activity