EBF contains a novel zinc coordination motif and multiple dimerization and transcriptional activation domains.

Early B cell factor (EBF) was identified and cloned as a transcription factor expressed specifically in B lymphocytes and adipocytes. This protein was also identified as olfactory factor 1 (Olf‐1) in olfactory neurons. In this study, we analyzed the structural requirements for DNA binding, homodimerization and transcriptional activation by EBF. A carboxyl‐terminal region, containing a repeat of alpha‐helices related to the helix‐loop‐helix motif, is important for dimerization of EBF in solution and can confer dimerization upon a heterologous DNA binding protein. The amino‐terminal DNA binding domain by itself is monomeric, but can mediate assembly of dimers on optimized and correctly spaced half‐sites. Mutational analysis of the DNA binding domain of EBF indicated that a novel zinc coordination motif consisting of H‐X3‐C‐X2‐C‐X5‐C is important for DNA recognition. Deletion analysis and transfer of regions of EBF onto a heterologous DNA binding domain identified a serine/threonine‐rich transcriptional activation domain. Moreover, the DNA binding domain of EBF can mediate transcriptional activation from optimized binding sites. Thus, EBF contains both a complex DNA binding domain that allows for dimerization and transcriptional activation, and additional dimerization and activation domains.