Nab1 and Nab2 are co-repressors that specifically interact with and repress transcription mediated by the three members of the NGFI-A (Egr-1, Krox24, zif/268) family of transcription factors [1]. This family consists of NAB conserved region 2, near the C-terminus of the protein. It is necessary for transcriptional repression by the Nab proteins [1]. It is also required for transcription activation by Nab proteins at Nab-activated promoters [2].

1: Nab1, a corepressor of NGFI-A (Egr-1), contains an active transcriptional repression domain. Swirnoff AH, Apel ED, Svaren J, Sevetson BR, Zimonjic DB, Popescu NC, Milbrandt J; Mol Cell Biol 1998;18:512-524. PMID:9418898

2: A novel activation function for NAB proteins in EGR-dependent transcription of the luteinizing hormone beta gene. Sevetson BR, Svaren J, Milbrandt J; J Biol Chem 2000;275:9749-9757. PMID:10734128