ATP synthase (complex V) !

ATP synthase is a molecular motor: protons flowing back into the matrix spin it, and each turn makes ATP from ADP and phosphate.

Updated 2026-11-01

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Key facts

Two parts: Fo, the proton channel with a c-ring that spins in the membrane, and F1 (α₃β₃γδε), the head in the matrix that makes ATP.
Binding-change mechanism (Boyer): each β subunit cycles through three states (open, loose, tight); one full turn releases 3 ATP.
In mammals the c-ring has 8 subunits: about 8 H⁺ per turn, roughly 2.7 H⁺ per ATP plus one to bring in phosphate.
Oligomycin plugs the Fo channel: ATP synthesis stops and, through respiratory control, so does the chain.

IF1 restrains it when the gradient collapses (ischemia), so it does not waste ATP running backwards.
Availability of ADP and phosphate drives it.

MT-ATP6 variants cause NARP or Leigh syndrome depending on the share of mutant copies (heteroplasmy).
Bacteria use the same machine; bedaquiline, for drug-resistant tuberculosis, blocks the mycobacterial ATP synthase.

Think of the answer, then tap the question to see it.

Which part of ATP synthase spins as protons pass?

The c-ring of the Fo sector, attached to the γ shaft, which turns inside the α₃β₃ head of F1.

What is the binding-change mechanism?

Each β subunit cycles through open, loose and tight states; the turning γ shaft changes its shape and releases the ATP already made.

Which inhibitor blocks the Fo channel of ATP synthase?

Oligomycin; it also slows the respiratory chain through respiratory control.

Which tuberculosis drug acts on the bacterial ATP synthase?

Bedaquiline, used in multidrug-resistant tuberculosis.

Educational information, not medical advice. For any symptom, see a health professional.

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Representative model, for educational purposes only.