Predicted to enable RNA polymerase II complex binding activity. Predicted to be involved in transcription elongation by RNA polymerase II. Predicted to act upstream of or within regulation of DNA-templated transcription; transcription elongation-coupled chromatin remodeling; and translational elongation. Predicted to be located in nucleus. Predicted to be part of DSIF complex. Orthologous to human SUPT4H1 (SPT4 homolog, DSIF elongation factor subunit).