E3 ubiquitin-protein ligase RING2 (RNF2)

H2AK119Ub gives a specific tag for epigenetic transcriptional repression and participates in X chromosome inactivation of female mammals. May be involved in the initiation of both imprinted and random X inactivation (By similarity).

Essential element of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class necessary to keep the transcriptionally repressive state of several genes, including Hox genes, throughout development (PubMed:16359901, PubMed:26151332). PcG PRC1 complex acts through chromatin remodeling and modification of histones, rendering chromatin heritably changed in its expressibility (PubMed:26151332).