SeeDev-binary@ldeleger:SeeDev-binary-9657152-3 JSONTXT

We have shown that the LEC1 polypeptide is homologous to the HAP3 subunit of the CBF class of eukaryotic transcriptional activators that includes NF-Y, CP1, and HAP2/3/4/5 (Johnson and McKnight 1989). The sequence similarity between LEC1 and other HAP3 subunits is restricted to the B domain, consistent with the finding that this domain is conserved evolutionarily (Li et al. 1992). Furthermore, amino acid residues of yeast and mammalian HAP3 subunits required for DNA binding and for interactions with other CBF subunits are conserved in LEC1 (Figure 4; [55] and [44]). Experiments demonstrating that yeast and mammalian CBF subunits can be combined to form DNA-binding complexes indicate that this amino acid sequence similarity underlies functional conservation ([6] and [43]).CBFs are heteroligomeric transcription factors, but it is not known whether the plant CBF is organized as its yeast counterpart into four nonhomologous subunits, HAP2, 3, 4, and 5, or is similar to the trimeric mammalian CBF ([24] and [27]).