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ATP Synthase: Mechanism

In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...
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Related Experiment Video

Updated: May 23, 2026

Phosphorus-31 Magnetic Resonance Spectroscopy: A Tool for Measuring In Vivo Mitochondrial Oxidative Phosphorylation Capacity in Human Skeletal Muscle
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Progressive Conduction Disease in a Mitochondrial Disorder.

Tânia Amaro1, Savia Bueno2, Cinthya Guirão2

  • 1Arrhythmia Unit, Heart Institute (Incor), University of São Paulo Medical School, São Paulo, Brazil; Cardiology Department, Clínica Girassol, Luanda, Angola.

JACC. Case Reports
|May 22, 2026
PubMed
Summary

Kearns-Sayre syndrome can cause unpredictable heart conduction abnormalities. Early permanent pacing is recommended, with implantable cardioverter-defibrillators considered for high-risk patients.

Keywords:
atrioventricular blockbradyarrhythmiaelectrocardiogrammitochondrial cytopathy

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Area of Science:

  • Neurology
  • Cardiology
  • Ophthalmology

Background:

  • Kearns-Sayre syndrome is a rare mitochondrial disorder.
  • It affects multiple organ systems, including the eyes and heart.
  • Progressive external ophthalmoplegia and pigmentary retinopathy are key features.

Purpose of the Study:

  • To report a case of Kearns-Sayre syndrome with significant cardiac conduction abnormalities.
  • To highlight the unpredictable progression of these abnormalities.
  • To discuss management strategies for cardiac involvement in Kearns-Sayre syndrome.

Main Methods:

  • Case report of a 45-year-old male patient.
  • Clinical evaluation including assessment of progressive external ophthalmoplegia and pigmentary retinopathy.
  • Cardiac evaluation with electrocardiogram and ambulatory monitoring.

Main Results:

  • The patient presented with bradyarrhythmia, exertional dyspnea, and fatigue.
  • Electrocardiogram and ambulatory monitoring revealed significant conduction abnormalities.
  • These findings are consistent with cardiac involvement in Kearns-Sayre syndrome.

Conclusions:

  • Conduction abnormalities in Kearns-Sayre syndrome can progress unpredictably.
  • Early permanent pacing should be strongly considered.
  • Implantable cardioverter-defibrillators may be indicated in patients with high-risk features.