A LITTLE LIGHTBULB MOMENT
Metabolism and bioenergetics
Phosphofructokinase-1 as glycolysis gatekeeper
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The bouncer who loves AMP and hates ATP
The idea behind the cue
PFK-1 is the rate-limiting enzyme of glycolysis. It is activated by AMP and fructose-2,6-bisphosphate, and inhibited by ATP and citrate. This helps match glucose breakdown to cellular energy status.
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Short & simple
The bouncer who loves AMP and hates ATP
Acronym
PAFA — Polka Avocados Fold Accordions.
Story
At the club door, PFK-1 checks the energy crowd. When AMP barges in waving an empty wallet, the bouncer opens the rope. When ATP and citrate arrive in limousines, the line slows to a crawl.
Connect the pieces
- P (Polka) → PFK-1: PFK-1 is the rate-limiting gatekeeper of glycolysis.
- A (Avocados) → AMP: AMP activates PFK-1 when cellular energy is low.
- F (Fold) → Fructose-2,6-bisphosphate: Fructose-2,6-bisphosphate also activates PFK-1 and pushes glycolysis forward.
- A (Accordions) → ATP: ATP inhibits PFK-1 when energy is plentiful, helping slow glucose breakdown.
- Polka · PFK-1: PFK-1 is the rate-limiting gatekeeper of glycolysis.
- Avocados · AMP: AMP activates PFK-1 when cellular energy is low.
- Fold · Fructose-2,6-bisphosphate: Fructose-2,6-bisphosphate also activates PFK-1 and pushes glycolysis forward.
- Accordions · ATP: ATP inhibits PFK-1 when energy is plentiful, helping slow glucose breakdown.
Know the limits
This is the classic allosteric control point; hexokinase and pyruvate kinase are also regulated but are not the main gatekeeper.
Further reading · OpenStax science textbooks ↗Check your understanding
Which molecule most directly activates phosphofructokinase-1?
A. AMP
B. ATP
C. Citrate
D. Acetyl-CoA
Reveal explanation
AMP
AMP signals low cellular energy and activates PFK-1. ATP and citrate inhibit it.