This gene encodes a component of the mediator complex (also known as TRAP, SMCC, DRIP, or ARC), a transcriptional coactivator complex thought to be required for the expression of almost all genes. The mediator complex is recruited by transcriptional activators or nuclear receptors to induce gene expression, by interacting with RNA polymerase II and promoting the formation of a transcriptional pre-initiation complex. A mutation in this gene has been associated with a novel infantile-onset neurodegenerative movement disorder. Alternatively spliced transcript variants have been identified. [provided by RefSeq, Mar 2015].