IWS1 Homolog (IWS1)

IWS1 a Pol II transcription elongation factor essential for mammalian cell proliferation. Interacts with Spt6 and Spt5. Three alternatively spliced human isoforms have been described. Loss-of-function mutations in AtIWS1 lead to overall dwarfism in Arabidopsis, reduced BR response, genome-wide decrease in BR-induced gene expression, and hypersensitivity to a transcription elongation inhibitor. Moreover, AtIWS1 interacts with BES1 both in vitro and in vivo. AtIWS1 is recruited to target genes by BES1 to promote gene expression during transcription elongation process. Recent genomic studies have indicated that a large number of genes could be regulated at steps after RNAPII recruitment; however, the mechanisms for such regulation have not been well established.