Structural and functional characterization of Runx1, CBFβ, and CBFβ-SMMHC

Core binding factors (CBFs) are heterodimeric transcription factors consisting of a DNA-binding CBFα subunit and non-DNA-binding CBFβ subunit. DNA binding and heterodimerization is mediated by a single domain in the CBFα subunit called the Runt domain, while sequences flanking the Runt domain confer other biochemical activities such as transactivation. On the other hand, the heterodimerization domain in CBFβ is the only functional domain that has been identified in this subunit. The biophysical properties of the Runt domain and the CBFβ heterodimerization domain, and the structures of the isolated domains as well as of the Runt domain-DNA, Runt domain-CBFβ, and ternary Runt domain-CBFβ-DNA complexes, have been characterized over the past several years, and are summarized in this review.