This entry represents a group of IWS1 plant homologues, including AtIWS1/2 from Arabidopsis. AtIWS1, also known as HNI9, is an evolutionary conserved component of the RNA polymerase II complex. It plays a role in N signaling by regulating several hundred N-responsive genes in roots []. It interacts with transcription factor BES1 and is involved in plant steroid hormone brassinosteroid regulated gene expression [].