Lehrstuhl für Biochemie, Universität Bochum, 4630 Bochum, Federal Republic of Germany.
Proc Natl Acad Sci U S A. 1982 Jan;79(1):6-10. doi: 10.1073/pnas.79.1.6.
Salivary glands of third-instar larvae of Drosophila melanogaster as well as Drosophila K(c) tissue culture cells have been irradiated in the presence of ecdysterone. Irradiation covalently links ecdysterone to a single cellular protein, which is similar, if not identical, in salivary glands and in K(c) cells. This protein has a molecular weight of 130,000 and it has the characteristics of a typical hormone-receptor molecule in terms of hormone-binding properties, translocation into the nucleus, and sedimentation characteristics. The yield of the photoinduced bonding of ecdysterone to receptor protein is around 15%. Ponasterone A competed with ecdysterone for the bonding. Also, ponasterone A itself reacted upon photoactivation with the beta-ecdysterone receptor protein in Drosophila tissue culture cells. We have previously shown that ecdysterone can be bonded upon irradiation to specific hormone-controlled puffs of polytene chromosomes of D. melanogaster third-instar larvae [Gronemeyer, H. & Pongs, O. (1980) Proc. Natl. Acad. Sci. USA 77, 2108-2112]. Because we have now identified the molecular target of the ecdysterone photoreaction, these data show that a hormone-receptor complex translocates to the nucleus and directly binds to the genes, which are under hormonal control. A quantitative assay of hormone-receptor complex in K(c) cells before and after hormone stimulation showed that ecdysterone does not regulate the synthesis and the available amount of its receptor. It was also observed that the translocated hormone-receptor complex resides in the nucleus as long as the hormone is present in the tissue culture medium.
黑腹果蝇三龄幼虫的唾液腺以及 Drosophila K(c)组织培养细胞在蜕皮激素存在的情况下被辐照。辐照使蜕皮激素与单个细胞蛋白共价结合，这种蛋白在唾液腺和 K(c)细胞中相似，如果不是完全相同的话。这种蛋白质的分子量为 130000，就激素结合特性、向核内转移以及沉降特性而言，它具有典型激素受体分子的特征。蜕皮激素与受体蛋白光诱导结合的产率约为 15%。ponasterone A 与蜕皮激素竞争结合。此外，ponasterone A 本身在 Drosophila 组织培养细胞中经光激活后与β-蜕皮激素受体蛋白反应。我们之前已经表明，在黑腹果蝇三龄幼虫的多线染色体上，特定的激素控制的膨突可以在照射时与蜕皮激素结合[Gronemeyer, H. & Pongs, O. (1980) Proc. Natl. Acad. Sci. USA 77, 2108-2112]。由于我们现在已经确定了蜕皮激素光反应的分子靶标，这些数据表明激素-受体复合物会转移到细胞核并直接与受激素控制的基因结合。在激素刺激前后对 K(c)细胞中的激素-受体复合物进行定量检测表明，蜕皮激素不会调节其受体的合成和可利用量。还观察到，只要组织培养基中存在激素，就会有转移的激素-受体复合物存在于细胞核中。
