A middle-affinity estrogen-specific binding protein in livers of vitellogenic and nonvitellogenic Xenopus laevis☆
[摘要] Administrationofestradiol-17βtomaleXenopuslaevisevokesmassiveliversynthesisoftheeggyolkprecursorprotein,vitellogenin,anditscognatemRNA.Sincepreviousexperimentshadimplicatedonlyanuclearestrogenreceptorinvitellogenesis,weexaminedXenopuslivercytosolforotherestrogen-bindingproteins.CytoplasmicextractsfromunstimulatedXenopuslivercontainhighlevels(approximately500,000sites/cell)ofanestrogen-specificbindingprotein.ThisproteinexhibitsaKdofapproximately4×10−8Mforestradiol-17β,bindsestrogenicsteroidsonly,andhasasedimentationcoefficientintherange2–3S.Itisnotaclassicalestrogenreceptor,asitdoesnottranslocateintothenucleusfollowingestrogenadministration.Wediscusspossiblefunctionsofthisprotein,whichincludearoleintheontogenyofthevitellogenicresponse,andinthecytoplasmictransportandstorageofestrogen.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
