Question

Protein kinase A is converted from an inactive state to an active state by binding

a. ATP.
b. calcium.
c. cAMP.
d. a and c.
e. all of the above

Answer 1

Protein kinase A is activated by the binding of cAMP, a second messenger synthesized from ATP, leading to the phosphorylation of target proteins and changes in cellular processes.

Step-by-step explanation:

Protein kinase A is activated from its inactive form by the binding of cyclic AMP (cAMP), which is a second messenger molecule. cAMP is synthesized from ATP by an enzyme called adenylyl cyclase. Once produced, cAMP binds to the regulatory subunits of Protein kinase A, causing a conformational change that releases the active catalytic subunits.

These active subunits of Protein kinase A then go on to phosphorylate various target proteins, altering their function and thus affecting various cellular processes. ATP is converted to cAMP by the enzyme adenylyl cyclase, and cAMP directly activates protein kinases. These protein kinases then phosphorylate substrate molecules, activating them and mediating changes in cellular processes.