ERH (enhancer of rudimentary homolog), also known as DROER, is a 104 amino acid transcriptional coregulator that is ubiquitously expressed and highly conserved among eukaryotes. ERH may play a role in cell cycle regulation and pyrimidine biosynthesis. ERH represses the function of the coactivator PCBD, preventing it from enhancing the activity of the tissue-specific transcription factor HNF-1 (hepatocyte nuclear factor-1). HNF-1 is a homeodomain transcription factor that binds DNA as a dimer and the HNF-1/DNA complex is stabilized by PCBD. By repressing PCBD, ERH disrupts the stability of the HNF-1/DNA complex, affecting the expression of multiple genes in the liver. The structure of ERH is characterized by a single domain consisting of three α-helices and four β-strands.
