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Bovine complex I is a complex of 45 different subunits.

Authors
  • Carroll, Joe
  • Fearnley, Ian M
  • Skehel, J Mark
  • Shannon, Richard J
  • Hirst, Judy
  • Walker, John E
Type
Published Article
Journal
Journal of Biological Chemistry
Publisher
American Society for Biochemistry & Molecular Biology (ASBMB)
Publication Date
Oct 27, 2006
Volume
281
Issue
43
Pages
32724–32727
Identifiers
PMID: 16950771
Source
Medline
License
Unknown

Abstract

Mammalian mitochondrial complex I is a multisubunit membrane-bound assembly with a molecular mass approaching 1 MDa. By comprehensive analyses of the bovine complex and its constituent subcomplexes, 45 different subunits have been characterized previously. The presence of a 46th subunit was suspected from the consistent detection of a molecular mass of 10,566 by electrospray ionization mass spectrometry of subunits fractionated by reverse-phase high pressure liquid chromatography. The component was found associated with both the intact complex and subcomplex Ibeta, which represents most of the membrane arm of the complex, and it could not be resolved chromatographically from subunit SGDH (the subunit of bovine complex I with the N-terminal sequence Ser-Gly-Asp-His). It has now been characterized by tandem mass spectrometry of intact protein ions and shown to be a C-terminal fragment of subunit SGDH arising from a specific peptide bond cleavage between Ile-55 and Pro-56 during the electrospray ionization process. Thus, the subunit composition of bovine complex I has been established. It is a complex of 45 different proteins plus non-covalently bound FMN and eight iron-sulfur clusters.

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