Anti-interacts with SUPT6H, CTD assembly factor 1 antibodies are used for the immunodetection of the protein encoded by the IWS1 gene. In humans, the canonical protein has a reported length of 819 amino acid residues and a mass of 92 kDa. Its subcellular localization is in the nucleus. Alternative splicing is reported to yield 3 different isoforms for this protein. A member of the IWS1 protein family, it is known to be a transcription factor which plays a key role in defining the composition of the RNA polymerase II (RNAPII) elongation complex and in modulating the production of mature mRNA transcripts. Post-translational modifications have been described, including phosphorylation. Other names for this target antigen include IWS1 homolog, IWS1, SUPT6H interacting protein, IWS1-like protein, interacts with Spt6, and protein IWS1 homolog. Gene orthologs have been identified in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.