The protein encoded by this gene shares similarity with BRE1 of S. cerevisiae. The protein encoded by this human gene is an E3 ubiquitin ligase that regulates chromosome structure by monoubiquitinating histone H2B. This protein acts as a putative tumor suppressor and positively regulates the p53 tumor suppressor as well as numerous histone H2A and H2B genes. In contrast, this protein also suppresses the expression of several protooncogenes and growth-related genes, including many genes that are induced by epidermal growth factor.