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. Expressed throughout the blastodermal layer in early embryos. At later stages, strong expression is observed in the brain, ventral cord and hindgut. Expressed at all stages. Belongs to the nuclear hormone receptor family. NR5 subfamily.