The comparison of the two previous proteins ends up with one principal common substructure which is, as expected, the Helix-Turn-Helix motif, responsible for the binding to the DNA.
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TRP Repressor of E. Coli |
Cro protein of Phage 434 |
The registration of the HTH motifs in the two proteins shows that not only is the backbone very well matched, but collateral chains are also pretty well conserved.