Glycolysis control — Which statements describe how ATP and ADP regulate the glycolytic pathway?

Introduction / Context:Glycolytic flux is tightly regulated to balance cellular energy status. Adenine nucleotides act as key signals: ATP indicates high energy charge and suppresses glycolysis, whereas ADP/AMP indicate low energy and stimulate it.

Given Data / Assumptions:

• Phosphofructokinase-1 (PFK-1) is a major control point.
• ATP and citrate inhibit, while ADP/AMP and fructose-2,6-bisphosphate activate.
• We evaluate multiple statements about regulation.

Concept / Approach:ATP binds allosteric sites on PFK-1 to decrease affinity for fructose-6-phosphate, reducing flux when energy is sufficient. ADP/AMP relieve this inhibition, enhancing glycolysis when energy is low. ATP also acts as a product and end-goal of the pathway, constituting feedback inhibition at several nodes, including pyruvate kinase regulation in some tissues.

Step-by-Step Solution:

Verification / Alternative check:In vitro PFK-1 kinetics demonstrate sigmoidal curves shifted by ATP and ADP/AMP, validating the regulatory scheme.

Why Other Options Are Wrong:

• Selecting only one statement ignores the integrated control by both ATP and ADP.

Common Pitfalls:Confusing ATP’s dual roles: substrate for kinases and allosteric inhibitor at high concentrations. The allosteric site is distinct from the catalytic site.

Final Answer:All of the above