Question

Protein kinase A (PKA) is: A) activated by covalent binding of cyclic AMP. B) affected by cyclic AMP only under unusual circumstances. C) allosterically activated by cyclic AMP. D) competitively inhibited by cyclic AMP. E) noncompetitively inhibited by cyclic AMP.

Answer 1

The correct answer is C.

Step-by-step explanation:

Protein kinase A (PKA) is one of these proteins for which cAMP is an allosteric activator that binds to the corresponding regulatory center in the enzyme, inducing dissociation of regulatory and catalytic subunits; The latter are thus arranged for the binding of the corresponding substrate proteins, which it phosphorylates at the expense of ATP and consequently modifies their activity. The phosphorylation and activation of glycogen phosphorylase depends on glycogen phosphorylase kinase, the latter enzyme that is a substrate for PKA.