Definition of the mitochondrial proteome by measurement of molecular masses of membrane proteins
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Contributed by John E. Walker, September 4, 2006
Abstract
The covalent structure of a protein is incompletely defined by its gene sequence, and mass spectrometric analysis of the intact protein is needed to detect the presence of any posttranslational modifications. Because most membrane proteins are purified in detergents that are incompatible with mass spectrometric ionization techniques, this essential measurement has not been made on many hydrophobic proteins, and so proteomic data are incomplete. We have extracted membrane proteins from bovine mitochondria and detergent-purified NADH:ubiquinone oxidoreductase (complex I) with organic solvents, fractionated the mixtures by hydrophilic interaction chromatography, and measured the molecular masses of the intact membrane proteins, including those of six subunits of complex I that are encoded in mitochondrial DNA. These measurements resolve long-standing uncertainties about the interpretation of the mitochondrial genome, and they contribute significantly to the definition of the covalent composition of complex I.
Footnotes
- *To whom correspondence should be addressed. E-mail: walker{at}mrc-dunn.cam.ac.uk
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Author contributions: J.E.W. designed research; J.C. performed research; J.C. and I.M.F. analyzed data; and J.E.W. wrote the paper.
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The authors declare no conflict of interest.
- Abbreviations:
- HILIC,
- hydrophilic interaction chromatography;
- ESI,
- electrospray ionization;
- ND,
- subunits of NADH dehydrogenase encoded in mitochondrial DNA
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Freely available online through the PNAS open access option.
- © 2006 by The National Academy of Sciences of the USA
