<p>High mobility group (HMG)-I proteins bind preferentially to the minor grooveof A.T-rich regions in double-stranded DNA [<cite idref="PUB00046104"/>, <cite idref="PUB00004432"/>]. DNA-binding of these, andseveral related, proteins is effected by an 11-residue domain known as anA.T-hook [<cite idref="PUB00046104"/>].</p><p>Within known HMG-I proteins are found three highly conserved regions, closely related to the consensus sequence TPKRPRGRPKK [<cite idref="PUB00046104"/>]. A synthetic oligopeptide with this sequence specifically binds to substrate DNA in amanner reminiscent of intact HMG-I proteins. Structure predictions suggestthat the peptide has a secondary structure similar to the anti-tumour andanti-viral drugs netropsin and distamycin [<cite idref="PUB00046104"/>]. These ligands, which also preferentially bind to A.T-rich DNA, effectivelycompete with both the synthetic peptide and the HMG-I proteins for DNA binding [<cite idref="PUB00046104"/>]. The peptide also contains novel structural features such as apredicted Asx bend, or "hook", at its N terminus, and laterally-projectingcationic Arg/Lys "bristles", which may play a role in the binding of HMG-Iproteins [<cite idref="PUB00046104"/>]. The predicted peptide structure, the A.T-hook, is a previouslyundescribed DNA-binding motif [<cite idref="PUB00046104"/>].</p><p>This family represents A.T-hook-like proteins. </p> AT hook-like