The protein encoded by this gene is a subunit of the Mediator complex, a large complex of proteins that functions as a transcriptional coactivator for most RNA polymerase II-transcribed genes. The encoded protein is involved in early development of the heart and brain. Defects in this gene are a cause of transposition of the great arteries, dextro-looped (DTGA).[provided by RefSeq, Jul 2010].