This gene encodes a small nuclear RING finger protein that mediates ubiquitylation of polysumoylated proteins. Deficiency of the encoded protein in mice leads to embryonic lethality and global DNA hypermethylation. A similar protein in humans is required for arsenic-induced degradation of promyelocytic leukemia protein in acute promyelocytic leukemia. Alternative splicing of this gene results in multiple transcript variants. A pseudogene for this gene has been identified on chromosome 10. [provided by RefSeq, Jan 2015]