The interaction of the wild-type p270 ARID-containing peptide with DNA is as strong as that of the wild-type Dri ARID-containing peptide. In both wild-type proteins, 80–90% of the signal is retained on the columns. The remainder comes off in the flow-through and the first wash, and presumably represents a fraction of peptide that did not bind due to impaired folding. The proline-to-alanine substitution has very little effect on the elution profile of either p270 or Dri, suggesting that this residue, though invariant, is not by itself critical for the maintenance of structural integrity in the domain.
