Fig. 4.

Site-specific mutational tolerance of the MLL3_SET protein. (A) Stability score (defined as the frequency change of a wild-type amino acid before and after screening) for each site of MLL3_SET. (B) Annotation of sites with high stability scores. The function of each site was experimentally confirmed in previous studies (41). The number of potential destabilizing mutations was predicted using the FoldX software. (C) Stability score of buried, partially buried, and solvent-exposed residues. Residues with relative solvent accessibility <0.05 were classified as buried, and residues with relative solvent accessibility >0.3 were classified as solvent exposed. Residues with relative solvent accessibility between 0.05 and 0.3 were classified as partially buried. P values were determined by two-tailed unpaired Student’s t tests. (D) Large-scale patterns of MLL3_SET’s stability score and the TRX/MLL sequence conservation score. A moving average (five-site window) of the stability score and sequence conservation score is plotted over protein sequence positions. Percentile ranks are used to plot the two scores on the same axis. Data are the mean ± SD of four technical replicates.