This large family of DNA binding helix-turn helix proteins includes Cro Swiss:P03036 and CI Swiss:P03034. Within the protein Swiss:Q5F9C2, the full protein fold incorporates a helix-turn-helix motif, but the function of this member is unlikely to be that of a DNA-binding regulator, the function of most other members, so is not necessarily characteristic of the whole family [1].

1: The crystal structure of NGO0477 from Neisseria gonorrhoeae reveals a novel protein fold incorporating a helix-turn-helix motif. Ren J, Sainsbury S, Nettleship JE, Saunders NJ, Owens RJ; Proteins. 2010;78:1798-1802. PMID:20196080