Question

How does PKA activity affect the cell?

Short answer

Enzymes involved in the metabolism of glycogen are among PKA's targets. The sequential activation of a heterotrimeric G protein, adenylate cyclase, and PKA results in the activation of glycogen phosphorylase, which makes glucose-6-phosphate available for glycolysis when epinephrine attaches to the -adrenergic receptor of a muscle cell.

Step-by-step solution

Step 1:Protein kinase A (PKA)

In eukaryotic cells, its main target is protein kinaseA (PKA; also known as cAMP-dependent protein kinase or cAPK), an enzymethat phosphorylates specific Ser or Thr residues of numerous cellular proteins.

Phosphorylation and dephosphorylation catalyzed by PKA.

The proportion of PKA in its active state and consequently the rate at which it phosphorylates its substrates are determined by the intracellular concentration of cAMP. PKA is an enzymethatphosphorylates specific Ser or Thr residues of numerous cellular proteins.The bifunctional enzyme is controlled by phosphorylation and dephosphorylation, which are catalyzed by PKA and a phosphoprotein phosphatase, as well as by various allosteric effectors. Therefore, hormones regulate the equilibrium between gluconeogenesis and glycolysis.