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Related Experiment Video

Updated: Jun 12, 2026

Inner Mitochondrial Membrane Sensitivity to Na+ Reveals Partially Segmented Functional CoQ Pools

Inner Mitochondrial Membrane Sensitivity to Na⁺ Reveals Partially Segmented Functional CoQ Pools

Published on: July 20, 2022

Quinone binding and reduction by respiratory complex I.

Maja A Tocilescu¹, Volker Zickermann, Klaus Zwicker

¹Molecular Bioenergetics Group, Medical School, Cluster of Excellence Frankfurt "Macromolecular Complexes," Center for Membrane Proteomics, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany. Mat2174@Columbia.edu

Biochimica Et Biophysica Acta

|May 25, 2010

Summary

Complex I, crucial for ATP production, facilitates electron transfer from NADH to ubiquinone. Research suggests an extended ubiquinone binding pocket at the 49-kDa/PSST subunit interface, with a conserved tyrosine critical for quinone reduction.

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Area of Science:

Biochemistry
Molecular Biology
Bioenergetics

Background:

Complex I (NADH:ubiquinone oxidoreductase) is vital for oxidative phosphorylation and ATP generation in cells.
It couples electron transfer from NADH to ubiquinone with proton pumping across membranes.
The precise mechanism of ubiquinone reduction within Complex I remains poorly understood.

Purpose of the Study:

To summarize and discuss experimental evidence on the ubiquinone binding site in Complex I.
To elucidate the role of specific subunits and residues in ubiquinone reduction.
To address current controversies regarding ubiquinone binding sites and reduction location.

Main Methods:

Review and synthesis of experimental data on Complex I structure and function.
Analysis of point mutation resistance patterns.
Discussion of conserved motifs and redox centers.

Main Results:

Evidence points to an extended ubiquinone binding pocket at the interface of the 49-kDa and PSST subunits.
A conserved tyrosine near iron-sulfur cluster N2 is critical for ubiquinone reduction.
A potential quinone exchange pathway from cluster N2 to the 49-kDa subunit's N-terminal β-sheet is proposed.
Hydrophobic inhibitors target the 49-kDa/PSST subunit interface.

Conclusions:

The 49-kDa/PSST subunit interface is a key location for ubiquinone reduction in Complex I.
Conserved residues and structural features play critical roles in quinone binding and reduction.
Further research is needed to resolve ongoing debates about ubiquinone binding sites and reduction mechanisms.