DR1, also known as NC2-beta, is a TBP (TATA box-binding protein) associated phosphoprotein that represses both basal and activated levels of transcription. The protein is phosphorylated in vivo and this phosphorylation affects its interaction with TBP. This protein contains a histone fold motif at the amino terminus, a TBP-binding domain, and a glutamine- and alanine-rich region. By selectively repressing polymerases II and III, DR1 may shift the physiological balance of transcriptional output in favor of polymerase I.
