Orphan receptor that acts as transcription activator in the absence of bound ligand. Binds specifically to an estrogen response element and activates reporter genes controlled by estrogen response elements. Induces the expression of PERM1 in the skeletal muscle (By similarity). Homodimer. Interacts with NRIP1, NCOA1 and NCOR2. Binds TLE1, PNRC1 and PNRC2. Binds GRIP1 (By similarity). Acetylated by PCAF/KAT2 (in vitro). No physiological activating ligand is known for this orphan receptor, but 4-hydroxytamoxifen and diethylstilbestrol act as inverse agonists and deactivate ESRRG. Belongs to the nuclear hormone receptor family. NR3 subfamily.