Metabolic Pathways and Regulation · USMLE Step 1

Which enzyme in glycolysis is subject to feedforward activation by fructose-1,6-bisphosphate (F-1,6-BP)?

  1. Hexokinase
  2. PFK-1
  3. Pyruvate kinase
  4. Phosphoglycerate kinase
Show answer and explanation

Correct answer: Pyruvate kinase

Pyruvate kinase is allosterically activated by F-1,6-BP (an upstream intermediate), which promotes downstream flux — an example of feedforward regulation that helps coordinate glycolytic throughput.

Difficulty: Medium Question 7 of 19

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