This gene encodes a subunit of RNA polymerase II, the polymerase responsible for synthesizing messenger RNA in eukaryotes. The product of this gene exists as a heterodimer with another polymerase subunit; together they form a core subassembly unit of the polymerase. Two similar genes are located nearby on chromosome 7q22.1 and a pseudogene is found on chromosome 7p13. [provided by RefSeq, Jul 2008].