What is the impact of serine phosphorylation on the interconversion between phosphorylase a and b forms?

• A. Phosphorylation converts phosphorylase a to phosphorylase b, increasing catalytic activity.
• B. Phosphorylation converts phosphorylase a to phosphorylase b, decreasing catalytic activity.
• C. Phosphorylation has no effect on the interconversion between phosphorylase forms.
• D. Phosphorylation converts phosphorylase b to phosphorylase a, increasing catalytic activity.

Answer: (D)