Ligand-activated transcription factor (By similarity). Involved in lifespan extension in a manner dependent upon mitochondrial function (PubMed:24107417). RNAi-mediated knockdown in a Rieske iron-sulfur protein isp-1 mutant background reduces life-span extension, causes a mild reduction in fertility, and reduces induction of expression of glutathione S-transferase gst-4. Belongs to the nuclear hormone receptor family.