Acts as a cofactor to fushi tarazu (ftz). Facilitates the binding of ftz to DNA. Binds the sequence element 5'-YCYYGGYCR-3' in the zebra element of ftz. Probably also functions as a receptor for a yet unknown ligand. Monomer; forms a complex with ftz. Expression in the parasegmental primordia of the embryonic blastoderm. First appears in blastoderm embryos. It is absent in subsequent embryo stages, and then reappears in late embryogenesis to be found in larvae, pupae and adults. Ftz-like pair-rule cuticular defects. Belongs to the nuclear hormone receptor family. NR5 subfamily.