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Updated: Aug 10, 2026
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Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria
Published on: January 7, 2022
Import and processing of heart mitochondrial cyclophilin D
1Department of Biochemistry and Molecular Biology, University College London, London, UK.
European Journal of Biochemistry
|July 17, 1999
Summary
Mitochondrial cyclophilin D, a key protein in the permeability transition pore, is located solely in the mitochondrial matrix. This finding suggests its interaction with the pore occurs on the inner membrane
Area of Science:
- Mitochondrial biology
- Protein import and localization
- Cellular respiration
Background:
- Cyclophilins are cyclosporin-A-binding proteins catalyzing prolyl peptide bond rotation.
- Mitochondrial cyclophilin D (CyD) is part of the permeability transition pore (PTP).
- The PTP involves adenine nucleotide translocase and voltage-dependent anion channel at mitochondrial contact sites.
Purpose of the Study:
- To determine the submitochondrial location of cyclophilin D.
- To investigate the import and processing of cyclophilin D in mammalian mitochondria.
Main Methods:
- In vitro expression of radiolabeled precursor cyclophilin D.
- Import of precursor protein into isolated rat heart mitochondria.
- Mitochondrial fractionation and SDS-PAGE analysis to identify protein location.
Main Results:
- Precursor cyclophilin D was imported and processed to a 21-kDa mature protein in a single step.
- The mature protein's size matched in vitro expressed mature CyD and purified mitochondrial CyD.
- Mitochondrial fractionation confirmed cyclophilin D exclusively localizes to the mitochondrial matrix.
Conclusions:
- Cyclophilin D is solely located in the mitochondrial matrix.
- Binding of cyclophilin D to the permeability transition pore occurs at the inner face of the mitochondrial inner membrane.
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