Activation of storage protein receptor by 20-hydroxyecdysone

A storage protein receptor was shown to be present in membranes of the pupal fat body of Sarcophaga peregrina, whereas membranes of the larval fat body contained a cryptic receptor. The molting hormone, 20-hydroxyecdysone, was essential for activation of the cryptic receptor to bind and incorporate the storage protein. The active receptor in the pupal fat body membrane was a protein with a molecular mass of 120-kdaltons. It was found that a 125-kdalton protein, a cryptic receptor for storage protein, present in the larval fat body membrane was converted to an active receptor in the presence of 20-hydroxyecdysone, without accompanying appreciable new protein synthesis.