NFYA: Proteins and Enzymes

The Y box is a CCAAT box which is bound by the heteromeric DNA binding protein, NFY (also known as CBF and CP1). Unlike the transcription factors C/EBP and CTF/NF1 which also bind CCAAT like sequences, NFY exhibits a strict binding requirement for this pentanucleotide sequence. Binding sites for this factor have been described for nearly 30% of all eukaryotic genes. Y/CCAAT sequences were frequently observed in the promoter proximal sequences. NF-Y is composed of 3 separate subunits (A,B and C) each of which is required for DNA binding. Each subunit has remained highly conserved throughout evolution. In fact, homologous yeast subunits can substitute for mammalian NF-Y in DNA-binding assays. The conserved core sequences of NF-YB and NF-YC contain a 70 aa region similar to the histone fold motif of nucleosomes H2A and H2B. The unique structure and evolutionary conservation of this transcription factor suggests that it plays a fundamental role in the readout of eukaryotic genetic information.