FIGURE 3.

A, shown is the prevalence of allolactose synthesis motif residues in β-galactosidase sequences. The bars with cross hatches represent sequences identified as having an allolactose synthesis motif, and open bars represent the remaining sequences. B, shown is the prevalence of conserved lac repressor residues in LacI-GalR family repressor sequences. The bars with cross hatches represent sequences identified as lac repressors, and open bars represent the remaining sequences. The datasets of protein sequences were obtained as described in the text (“see Experimental Procedures”).