<p>The myb family can be classified into three groups: the myb-type HTH domain, which binds DNA, the SANT domain, which is a protein-protein interaction module (see <db_xref db="PROSITEDOC" dbkey="PDOC51293"/>) and the myb-like domain that can be involved in either of these functions.</p><p>The myb-type HTH domain is a DNA-binding, helix-turn-helix (HTH) domain of ~55 amino acids, typically occurring in a tandem repeat in eukaryotic transcription factors. The domain is named after the retroviral oncogene v-myb, and its cellular counterpart c-myb, which encode nuclear DNA-binding proteins that specifically recognise the sequence YAAC(G/T)G [<cite idref="PUB00004032"/>, <cite idref="PUB00001154"/>]. Myb proteins contain three tandem repeats of 51 to 53 amino acids, termed R1, R2 and R3. This repeat region is involved in DNA-binding and R2 and R3 bind directly to the DNA major groove. The major part of the first repeat is missing in retroviral v-Myb sequences and in plant myb-related (R2R3) proteins [<cite idref="PUB00043781"/>]. A single myb-type HTH DNA-binding domain occurs in TRF1 and TRF2. The 3D-structure of the myb-type HTH domain forms three alpha-helices [<cite idref="PUB00025569"/>]. The second and third helices connected via a turn comprise the helix-turn-helix motif. Helix 3 is termed the recognition helix as it binds the DNA major groove, like in other HTHs.</p> Transcription regulator HTH, Myb-type, DNA-binding