Evolutionary constraints on protein sequence and structure features. Error bars represent 95th percentile confidence intervals from bootstrap resampling. (a) For proteins shorter than 500 residues, short proteins have high A/S ratios. (b) Buried residues are under stronger selection. The 95th percentile confidence intervals of the A/S ratio are [0.23, 0.25] for buried residues, and [0.30, 0.32] for exposed residues. (c) Loop residues have relaxed evolutionary constraints. The 95th percentile confidence intervals of the A/S ratio are [0.25, 0.26] for residues in alpha-helices, [0.24, 0.27] for residues in beta-strands, and [0.30, 0.32] for residues in loops. (d) Proteins with disordered regions are more conserved, while disordered residues are under lower selective pressure. (e) Residues in low complexity regions evolve faster.