You are examining the regulatory control of glycolysis by addition of a novel compound to a hepatocyte cell culture system. Your studies demonstrate that addition of the compound decreases the kinase activity of PFK2 while simultaneously increasing the phosphatase activity of the enzyme. This response most closely reflects which of the following naturally occurring controls exerted on PFK2?

Question

Quizplus · Accepted Answer

Phosphorylation by cAMP-dependent protein kinase (PKA) decreases the kinase activity and increases the phosphatase activity of PFK2, similar to the effect of the novel compound.  When PFK2 is phosphorylated, via the action of PKA, its activity shifts from a kinase to a phosphatase. Within hepatocytes, this shift in catalytic activity of PFK2 results in less activation of the rate-limiting enzyme of glycolysis, PFK1, to ensure the liver produces glucose via gluconeogenesis instead of oxidizing the sugar.

You Are Examining the Regulatory Control of Glycolysis by Addition