Implicated in the regulation of ecdysone-triggered gene hierarchies. Probably plays a key role in mediating the regulation of the larval molt by 20-OH-ecdysone. In mid instar larvae salivary glands, levels increase during puff stage 1, then remain relatively constant until the premetamorphic pulse of ecdysone at puff stage 5. Levels increase again in late larvae at puff stages 9-10. At puff stage 1 expression is also seen in the gut. Levels are low in the gut, Malpighian tubules, fat body and wing disks between stages 1 and 11. The expression of this protein is developmentally regulated and is correlated with the 20-OH-ecdysone induced activity of puff 75B. Belongs to the nuclear hormone receptor family. NR1 subfamily.