This gene encodes a member of the estrogen receptor-related receptor (ESRR) family, part of the nuclear hormone receptor superfamily. ESRR members share a DNA-binding domain with two C4-type zinc finger motifs and act as orphan nuclear receptors. They bind estrogen and steroidogenic factor 1 response elements, activating genes in the absence of ligands. ESRRs are closely related to estrogen receptors (ER), targeting similar genes and co-regulators, often interfering with ER-mediated estrogen responses. The protein encoded by this gene activates DNA methyltransferase 1 (Dnmt1) expression, influences cell proliferation and estrogen signaling in breast cancer, and negatively regulates osteoblast differentiation and bone formation. Multiple alternatively spliced transcript variants produce isoforms with different N-terminal regions.