MED20 is a subunit of the Mediator complex, a multiprotein coactivator of RNA transcription that interacts with DNA-bound transcriptional activators, RNA polymerase II (see MIM 180660), and general initiation factors. Recombinant human MED20 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.