Subcellular location of proteins and PPIs. (a) Numbers of proteins with at least one Gene Ontology (GO) term for cellular component (CC). For each species, the six bars from left to right represent the numbers of proteins (1) in our in-house dataset (purple), (2) with at least one GO CC (orange), (3) with a GO CC term after filtration based on evidence code (4) with a GO term after collapse of terms (green), (5) with only one GO term (blue), and (6) with multiple GO terms (grey). Bars (5) and (6) are numbers after filtration based on evidence and collapse of GO terms. (b) Proportional distribution of protein numbers according to cellular compartment. Proteins are counted once in each annotated location; those with multiple locations have been counted a corresponding number of times. The bar on the far left represents overall proportion of compartment. The other three bars represent soluble (left), soluble secreted (middle), and membrane (right) proteins. GO CC terms were recorded after quality filtration and collapse. (c) For each species, numbers of co-PPIs in the three most-abundant CC locations. Both interacting proteins are required to have least one GO CC term. For a-c: CMV (cytoplasmic membrane-bound vesicle), Cyt (cytoplasm), End (endosome), ER (endoplasmic reticulum), ExM (extra cellular matrix), ExR (extra cellular region), Gol (golgi apparatus), LP (lipid particle), Lys (lysosome), Mel (melanosome), Mit (mitochondrion), Nuc (nucleus), Per (peroxisome), PM (plasma membrane), SV (synaptic vesicle).