Glucose release (relative units): epinephrine 100, cAMP analog 95, epinephrine + PKA inhibitor 8, buffer 5. The researcher concludes the pathway is epinephrine -> cAMP -> PKA -> glycogen breakdown.
What additional treatment would distinguish PKA's role from a downstream phosphatase?
- A
Increase the epinephrine concentration
- Bcheck_circle
Add a phosphatase inhibitor and observe whether the response is prolonged
- C
Use a different cell type
- D
Replace epinephrine with insulin
Explanation
A phosphatase reverses PKA-mediated phosphorylation of glycogen phosphorylase. Inhibiting phosphatase should prolong or amplify glucose release, distinguishing the dephosphorylation step from PKA-driven phosphorylation.