DR1 is a phosphoprotein that inhibits both basal and activated levels of transcription. DR1 is phosphorylated in vivo which affects its interaction with TBP. DR1 has 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 alters the physiological balance of transcriptional output in favor of polymerase I.
