POLR2E, also as known as DNA-directed RNA polymerases I, II, and III subunit RPABC1, belongs to the archaeal RpoH/eukaryotic RPB5 RNA polymerase subunit family. POLR2E is the fifth largest subunit of RNA polymerase II, the polymerase responsible for synthesizing messenger RNA in eukaryotes. This subunit is shared by the other two DNA-directed RNA polymerases and is present in two-fold molar excess over the other polymerase subunits. POLR2E is a DNA-dependent RNA polymerase that catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Recombinant human POLR2E protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.