BRD3 was identified based on its homology to the gene encoding the RING3 protein, a serine/threonine kinase. This protein localizes to 9q34, a region which contains several major histocompatibility complex (MHC) genes. The function of the encoded protein is not known. Recombinant human BRD3 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.