Selective pressures on protein subcellular localization. Error bars represent 95th percentile confidence intervals from bootstrap resampling. (a) Analysis of SignalP predictions suggests that while there is no significant difference in selective pressure between secreted and non-secreted proteins, residues within signal peptides are evolving faster. (b) TMHMM predictions show no difference in A/S ratios between membrane proteins and non-membrane proteins, transmembrane segments and non-transmembrane segments. (c) LOCtree predictions of protein subcellular localization indicate extracellular proteins (1,587 proteins) are under more relaxed selective pressure than cytoplasmic proteins (2,105) and nuclear proteins (5,431). (d) GO cellular component annotations suggest extracellular proteins (522 proteins) are under more relaxed selective pressure than cytoplasmic proteins (1,030) and nuclear proteins (1,961), while membrane proteins (2,715) fall in between. The 95th percentile confidence intervals of the A/S ratio are [0.27, 0.33] for extracellular proteins, [0.21, 0.24] for nuclear proteins, [0.22, 0.26] for cytoplasmic proteins, and [0.26, 0.29] for membrane proteins.