Related Experiment Video
Updated: Aug 13, 2026

Visualization of ATP Synthase Dimers in Mitochondria by Electron Cryo-tomography
Published on: September 14, 2014
Carbonic anhydrase subunits form a matrix-exposed domain attached to the membrane arm of mitochondrial complex I in
Stephanie Sunderhaus1, Natalya V Dudkina, Lothar Jänsch
1Institut für Angewandte Genetik, Universität Hannover, Herrenhäuser Strasse 2, D-30419 Hannover, Germany.
Abstract:
Complex I of Arabidopsis includes five structurally related subunits representing gamma-type carbonic anhydrases termed CA1, CA2, CA3, CAL1, and CAL2. The position of these subunits within complex I was investigated. Direct analysis of isolated subcomplexes of complex I by liquid chromatography linked to tandem mass spectrometry allowed the assignment of the CA subunits to the membrane arm of complex I. Carbonate extraction experiments revealed that CA2 is an integral membrane protein that is protected upon protease treatment of isolated mitoplasts, indicating a location on the matrix-exposed side of the complex. A structural characterization by single particle electron microscopy of complex I from the green alga Polytomella and a previous analysis from Arabidopsis indicate a plant-specific spherical extra-domain of about 60 A in diameter, which is attached to the central part of the membrane arm of complex I on its matrix face. This spherical domain is proposed to contain a heterotrimer of three CA subunits, which are anchored with their C termini to the hydrophobic arm of complex I. Functional implications of the complex I-integrated CA subunits are discussed.
Related Concept Videos
Electron Transport Chain: Complex I and II
ROS generation is regulated and maintained at moderate levels necessary...
The Supercomplexes in the Crista Membrane
The Inner Mitochondrial Membrane
Electron Transport Chain: Complex III and IV
Chemiosmosis
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Electron Transport Chains
The ETC is comprised of...

