RNA polymerase-associated protein LEO1 is an enzyme that in humans is encoded by the LEO1 gene. LEO1, parafibromin (CDC73; MIM 607393), CTR9 (MIM 609366), and PAF1 (MIM 610506) form the PAF protein complex that associates with the RNA polymerase II subunit POLR2A (MIM 180660) and with a histone methyltransferase complex
