The PAF1 complex is a multifunctional complex. Involved in transcription initiation via genetic interactions with TATA-binding proteins. Involved in elongation. It regulates 3'-end formation of snR47 by modulating the recruitment or stable association of NRD1 and NAB3 with RNA polymerase II. Also has a role in transcription-coupled histone modification. Required for activation of RAD6 ubiquitin conjugate and the BRE1 ubiquitin ligase which ubiquitinate 'Lys-126' histone H2B. Activates the SET1 histone methyltransferase complex for methylation of 'Lys-4' of histone H3 and for methylation of 'Lys-73' of histone H3 by DOT1 and 'Lys-36' of histone H3 by SET2. Important for TATA site selection by TBP. Directly or indirectly regulates the DNA-binding properties of SPT15, the TATA box-binding protein, and the relative activities of different TATA elements. Component of the PAF1 complex which consists of at least CDC73, CTR9, LEO1, PAF1 and RTF1. Present with 6510 molecules/cell in log phase SD medium.