To get an overview of our proteomic data the identified and quantified proteins were analysed further using different bioinformatics tools. The proteins were first classified using the gene ontology (GO) annotations of their known subcellular locations (Fig. 1D ) and biological functions (Fig. 2, Fig. S2 ). Most of the known mitochondrial proteins identified in this study were found from the mitochondrial fraction. In addition to mitochondrial proteins, most of the identified lysosomal and endoplasmic reticulum (ER) proteins were located in the mitochondrial fraction implying that these subcellular organelles are also enriched in the mitochondrial fraction. Proteins with a known cytosolic localization were most abundant in the cytoplasmic fraction. Many cytosolic proteins, however, also have a nuclear annotation which can be seen in our data as a large number of 'nuclear' proteins in the cytoplasmic fraction. In the nuclear fraction, proteins with a nuclear annotation were clearly the most abundant.