Subunits of complex I from Y. lipolytica indicating proteins missing in subcomplex nb8mΔ (bold and underlined) according to combined data from dSDS-PAGE, LILBID-MS, and ESI-MS.

aUnpublished data. Purified subcomplex nb8mΔ was run on BN-PAGE, subjected to tryptic in-gel digestion and analysed by nano liquid chromatography ESI-MS.bMolecular mass includes 1,267.3 Da for the hexa-histidine tag and hexa-alanine spacer [18].cNot determined; the hydrophobic subunits ND2, ND6, and ND4L are not reliably identified by ESI-MS and subunit ST1 is known to dissociate from the complex during BN-PAGE [13].dAccessory subunits are numbered according to their molecular mass. Not that this numbering is not identical to Morgner et al. [13].eMolecular mass includes 564.7 Da for covalently bound phosphopantetheine-hydroxy-tetradecanoate.fSubunit NUUM was recently found in Y. lipolytica complex I [35], but we found an intron near the N-terminus resulting in a larger protein that lacked the N-terminal methionine. This was confirmed by peptide identification with LC/ESI-MS analysis at 100% sequence coverage (not shown).gSubunit NEBM was identified and characterized recently in another study from our laboratory (E. Nübel et al., in preparation).