title: Juvenile hormone receptors in insect larval epidermis: identification by photoaffinity labeling.
abstract: Tritiated photoaffinity analogs of the natural lepidopteran juvenile hormones, JH I and II [epoxy[3H]bishomofarnesyl diazoacetate ([3H]EBDA) and epoxy[3H]homofarnesyl diazoacetate ([3H]EHDA)], and of the JH analog methoprene [[3H]methoprene diazoketone ([3H]MDK)] were synthesized and used to identify specific JH binding proteins in the larval epidermis of the tobacco hornworm (Manduca sexta). EBDA and EHDA specifically photolabeled a 29-kDa nuclear protein (pI 5.8). This protein and a second 29-kDa protein (pI 6.0) were labeled by MDK, but excess unlabeled methoprene or MDK only prevented binding to the latter. These 29-kDa proteins are also present in larval fat body but not in epidermis from either wandering stage or allatectomized larvae, which lack high-affinity JH binding sites. A 29-kDa nuclear protein with the same developmental specificity as this JH binder bound the DNA of two larval endocuticle genes. A 38-kDa cytosolic protein was also specifically photolabeled by these photoaffinity analogs. The 29-kDa nuclear protein is likely the high-affinity receptor for JH that mediates its genomic action, whereas the 38-kDa cytosolic protein may serve as an intracellular carrier for these highly lipophilic hormones and hormone analogs.
authors.affiliation: Department of Zoology, University of Washington, Seattle, WA 98185, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Palli
authors.forename: E O
authors.initials: EO
authors.lastname: Osir
authors.forename: W
authors.initials: W
authors.lastname: Eng
authors.forename: M F
authors.initials: MF
authors.lastname: Boehm
authors.forename: M
authors.initials: M
authors.lastname: Edwards
authors.forename: P
authors.initials: P
authors.lastname: Kulcsar
authors.forename: I
authors.initials: I
authors.lastname: Ujvary
authors.forename: K
authors.initials: K
authors.lastname: Hiruma
authors.forename: G D
authors.initials: GD
authors.lastname: Prestwich
authors.forename: L M
authors.initials: LM
authors.lastname: Riddiford