Question

How is PKA activity regulated?

Short answer

The PKA (protein kinase A) is activated by cAMP, a second messenger that is made by adenylate cyclase on hormone-stimulated activation of a heterotrimeric G protein.

Step-by-step solution

Targets of PKA

The targets of PKA include enzymes involved in glycogen metabolism. For example, when epinephrine binds to theβ-adrenergic receptor of a muscle cell, the sequential activation of a heterotrimeric G protein, adenylate cyclase and PKA lead to the activation of glycogen phosphorylase, thereby making glucose-6-phosphate available for glycolysis in a “fight-or-flight” response.

PKA is activated by cAMP

The PKA is activated by cAMP.The effects of protein kinases are reversed by the activity of protein phosphatases and also regulated by phosphatases.A small change in [cAMP] results in a large change in the fraction of phosphorylated enzymes.