Tissue-specific component of the SMC5-SMC6 complex, a complex involved in repair of DNA double-strand breaks by homologous recombination. The complex may promote sister chromatid homologous recombination by recruiting the SMC1-SMC3 cohesin complex to double- strand breaks. The complex is required for telomere maintenance via recombination and mediates sumoylation of shelterin complex (telosome) components. . Acts as a repressor of nuclear receptor-dependent transcription possibly by interfering with CREBBP-dependent coactivation. May function as a coinhibitor of other CREBBP/EP300- dependent transcription factors. . This is the function of EID3 (EP300 interacting inhibitor of differentiation 3, Ensembl gene identifier ENSG00000255150).