Binds to an ERR-alpha response element (ERRE) containing a single consensus half-site, 5'-TNAAGGTCA-3'. Can bind to the medium-chain acyl coenzyme A dehydrogenase (MCAD) response element NRRE-1 and may act as an important regulator of MCAD promoter. Binds to the C1 region of the lactoferrin gene promoter. Requires dimerization and the coactivator, PGC-1A, for full activity. The ERRalpha/PGC1alpha complex is a regulator of energy metabolism. Induces the expression of PERM1 in the skeletal muscle. Binds DNA as a monomer or a homodimer. Interacts (via the AF2 domain) with coactivator PPARGC1A (via the L3 motif); the interaction greatly enhances transcriptional activity of genes involved in energy metabolism. Interacts with PIAS4; the interaction enhances sumoylation. Interacts with MAPK15; promotes re-localization of ESRRA to the cytoplasm through a XPO1-dependent mechanism then inhibits ESRRA transcriptional activity. Co-localizes to the cytoplasm only in presence of MAPK15. Induced by PGC1alpha in a number of specific cell types including heart, kidney and muscle. Phosphorylation on Ser-19 enhances sumoylation on Lys-14 increasing repression of transcriptional activity. Sumoylated with SUMO2. Main site is Lys-14 which is enhanced by phosphorylation on Ser-19, cofactor activation, and by interaction with PIAS4. Sumoylation enhances repression of transcriptional activity, but has no effect on subcellular location nor on DNA binding. Reversibly acetylated. Acetylation by PCAF/KAT2 at Lys-129, Lys-138, Lys-160 and Lys-162 and PCAF/KAT2 decreases transcriptional activity probably by inhibiting DNA-binding activity; deacetylation involves SIRT1 and HDAC8 and increases DNA-binding. Belongs to the nuclear hormone receptor family. NR3 subfamily. Extended N-terminus.