ERH, also known as enhancer of rudimentary homolog, is a ubiquitously expressed transcriptional coregulator that is highly conserved among eukaryotes. It may play a role in cell cycle regulation and pyrimidine biosynthesis. It has two casein kinase II phosphorylation sites that are thought to disrupt the ability of ERH to dimerize. Recombinant human ERH protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.