The Nuclear factor I (NFI) family of site-specific DNA-binding proteins (also known as CTF or CAAT box transcription factor) functions both in viral DNA replication and in the regulation of gene expression in higher organisms. The N-terminal 200 residues contains the DNA-binding and dimerisation domain, but also has an 8-47 residue highly conserved region 5' of this, whose function is not known. Deletion of the N-terminal 200 amino acids removes the DNA-binding activity, dimerisation-ability and the stimulation of adenovirus DNA replication [1].

1: Chicken NFI/TGGCA proteins are encoded by at least three independent genes: NFI-A, NFI-B and NFI-C with homologues in mammalian genomes. Rupp RA, Kruse U, Multhaup G, Gobel U, Beyreuther K, Sippel AE; Nucleic Acids Res. 1990;18:2607-2616. PMID:2339052