When ATP is abundant, inhibition of phosphofructokinase is important because it...

• A. Facilitates gluconeogenesis to maintain euglycemia
• B. Allows the cell to divert glucose to be stored as glycogen
• C. Promotes catabolism
• D. Enhances the TCA Cycle

Answer: (B)

When ATP is high, the cell wants to slow down glycolysis to avoid wasting glucose. Phosphofructokinase-1 is the gatekeeper of glycolysis and is allosterically inhibited by ATP. With PFK-1 inhibited, glucose-6-phosphate begins to accumulate and can be redirected into glycogen synthesis in liver and muscle. This stores glucose as glycogen for future energy needs rather than burning it right away. Gluconeogenesis, catabolic flux, and pushing the TCA cycle would not be favored in a high-ATP state, whereas storing glucose as glycogen fits the energy-rich conditions.