Bovine complex I is a complex of 45 different subunits.

TitleBovine complex I is a complex of 45 different subunits.
Publication TypeJournal Article
Year of Publication2006
AuthorsCarroll, J, Fearnley, IM, J Skehel, M, Shannon, RJ, Hirst, J, Walker, JE
JournalJ Biol Chem
Date Published2006 Oct 27
KeywordsAnimals, Cattle, Chromatography, High Pressure Liquid, Electron Transport Complex I, Mitochondria, Heart, Molecular Weight, Protein Subunits, Spectrometry, Mass, Electrospray Ionization

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.

Alternate JournalJ. Biol. Chem.
Citation Key10.1074/jbc.M607135200
PubMed ID16950771
Grant ListMC_U105663141 / / Medical Research Council / United Kingdom
MC_U105663148 / / Medical Research Council / United Kingdom