title: Characterization of cytoplasmic ecdysteroid receptors in the hypodermis of the crayfish, Orconectes limosus.
abstract: [3H]Ecdysone, [3H]20-OH-ecdysone and [3H]ponasterone A were specifically bound by the 120 000 g supernatant of the homogenate from crayfish hypodermis. According to the HPLC test, the bound hormone was not metabolized. Analysis of the cytosol receptor by sucrose-density-gradient centrifugation, gel filtration and enzymatic degradation revealed the protein character of the receptor, a molecular weight of 70 000-80 000 D, and 5S. The binding capacity was rapidly lost after treatment with N-ethyl-maleimide or heating for 10 min at 60 degrees C. Optimal conditions for the demonstration of the receptor were incubation at 0-8 degrees C for 30 min and a salt concentration of 120 mM. A sequence of moulting hormones, and steroid hormones without moulting hormone activity were tested for ligand specificities. Estimation KD values yielded 3-6 x 10(-11) M for ponasterone A, 2-3 x 10(-9) M for 20-OH-ecdysone and 2 x 10(-8) M for ecdysone.
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000378:metabolism; D004441:Ecdysterone / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006358:Hot Temperature; D007700:Kinetics; D008970:Molecular Weight; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*
chemical_list: D011956:Receptors, Cell Surface; D004441:Ecdysterone; D005033:Ethylmaleimide