InterPro domain: IPR027113

The eukaryotic transcription factors NF-Y, also known as CCAAT-binding factors (CBF) or heme activator protein (HAP), bind to a CCAAT element in the promoters of a wide variety of genes, to regulate its expression. They consists of three distinct subunits: NF-YA (also known as CBF-B or HAP2), NF-YB (CBF-A or HAP3) and NF-YC (CBF-C or HAP5). The NF-YB subunit consists of three regions, an N-terminal A domain, a central conserved B domain, and a C-terminal C domain. The B domain is highly conserved and the most important part of the NF-YB subunit, as it is required for the interaction with NF-YA and NF-YC to form the heterotrimeric complex and contain the evolutionarily-conserved DNA binding domain [ 1 , 2 , 3 ]. There is only a gene encoding NF-YB in yeast and animals, but in plants there are gene families encoding this subunit, for example in Arabidopsis there are at least 10 NF-YB genes [ 4 ].

This entry represents CBF-A or NF-YB from vertebrates and HAP3 from yeast. The Kluyveromyces lactis HAP3 protein has been predicted to contain a 4-cysteine zinc finger, which is thought to be present in similar HAP3 and CBF subunit A proteins, in which the third cysteine is replaced by a serine [ 5 ].

1. Purification and molecular cloning of the "A" chain of a rat heteromeric CCAAT-binding protein. Sequence identity with the yeast HAP3 transcription factor. J. Biol. Chem. 265, 22480-6
2. Evolutionary variation of the CCAAT-binding transcription factor NF-Y. Nucleic Acids Res. 20, 1087-91
3. Genome-wide identification and characterization of the NF-Y gene family in grape (vitis vinifera L.). BMC Genomics 17, 605
4. Identification and characterization of NF-YB family genes in tung tree. Mol. Genet. Genomics 290, 2187-98
5. Sequence of the HAP3 transcription factor of Kluyveromyces lactis predicts the presence of a novel 4-cysteine zinc-finger motif. Mol. Gen. Genet. 245, 96-106