PAF is a five-subunit protein complex composed of Paf1, Cdc73, Leo1, Rtf1 and Ctr9, which was first purified from yeast. The yeast PAF (yPAF) complex interacts with RNA polymerase II and coordinates the setting of histone marks associated with active transcription. The human PAF (hPAF) complex shares four subunits with yPAF (hCtr9, hPaf1, hLeo1 and Cdc73), but contains an additional higher eukaryotic-specific subunit, hSki8. In addition to coordinating events during transcription (initiation, promoter clearance and elongation); PAF also coordinates events in RNA quality control.