Figure 6

Observed and predicted site-specific amino acid distribution ${\pi }_{c_{i/<c>}}$(a), divided by the expected frequencies under mutation alone w_AA(a), for (a) the mutation models 1 ('opt. freq. at β ≡ 0'), (b) mutation model 2 ('constant'), (c) mutation model 4 ('opt. freq.'), and (d) mutation model 5 ('CpG'). For the theoretical models where mutation satisfies detailed balance, ${\pi }_{c_i}$(a)/w_AA(a) ∝ exp [-β _i h(a)], so that the slope of the plot represents β _i at this site class. For illustration, site class with c _i /<c> ∈ [0.435, 0.545] was selected. Full symbols show the observed distributions obtained from sequences in the PDB, whereas the open symbols and the lines display the mean-field model.