Cloning and Characterization of Ecdysone Receptor and Ultraspiracle cDNAs fromSpodoptera litura

Abstract: The insect molting hormone, ecdysone, induces a series of events critical for ecdysis, beginning with the formation of a complex between ecdysteroid receptor (EcR) and its partner protein, ultraspiracle (Usp). In the present study, we cloned cDNAs encoding EcR and Usp by RT-PCR and 5′-/3′-RACE from the common cutworm, Spodoptera litura, a destructive agricultural pest insect in East Asia. Hexahistidine-tagged recombinant EcR and Usp of S. litura were expressed in E. coli, and the proteins, after refolding, exhibited the specific binding to an ecdysone analogue in vitro.