We are testing the hypothesis that oxidized peptides are released from stressed mitochondria and contribute to retrograde signalling (Møller IM & Sweetlove LJ 2010 Trends Plant Sci 15, 370-374). However, there is a large gap between the number of experimentally verified mitochondrial proteins (~450) and in silico-predicted mitochondrial proteins (2000-3000). Thus, before starting to look for oxidized peptides, we wanted to expand the current compendium of plant mitochondrial proteins while obtaining what could be termed the "baseline proteome" from our model organelle, the potato tuber mitochondrion. Its proteome was characterized in depth by a combination of gel electrophoresis prefractionation of proteins and liquid chromatography-tandem mass spectrometry of ensuing peptides from in-gel digestion. The results indicate that we have a close to complete coverage. The presence and absence of a number of interesting proteins will be discussed.