Distinct type-2A protein phosphatases activate HMGCoA reductase and acetyl-CoA carboxylase in liver.

Acetyl-CoA carboxylase and HMGCoA reductase are inactivated by the same AMP-activated protein kinase and are activated by type-2A protein phosphatase. To determine whether the same species of protein phosphatase-2A were involved, we studied the interconversion of acetyl-CoA carboxylase and HMGCoA reductase in isolated rat hepatocytes. We show that (i) these enzymes are differently regulated in hepatocytes and (ii) the species of type-2A protein phosphatase involved in their activation are different and can be separated by anion-exchange chromatography.