Pax6 is a transcription factor found in humans that is essential for development of the eye, nose, pancreas and central nervous system. It contains a 128-amino acid paired DNA-binding domain made up of a an amino-terminal subdomain, extended linker region and carboxy-terminal subdomain (green on the 3D molecule). These subdomains make extensive DNA contacts over a 26 base pair site. The extended linker makes minor groove contacts over an 8 base pair site and the carboxy-terminal forms a helix-turn-helix unit which makes base contacts with the major groove of the DNA. The amino-terminal also forms a helix-turn-helix unit and its structure has an approximate two-fold symmetry axis with the C-subdomain polypeptide backbone. Internestingly, the C domain in the corresponding paired domain found in Drosophila (PRD) does not make any DNA contacts, which is thought to be due to several differences in amino acids.
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