Institute of General Zoology and Endocrinology, Ulm University, Albert-Einstein-Allee 11, Ulm, Germany.
Insect Mol Biol. 2011 Dec;20(6):701-11. doi: 10.1111/j.1365-2583.2011.01099.x. Epub 2011 Sep 7.
Transcriptional activity of nuclear receptors is the result of transactivation capability and receptor protein concentration. The concentration of ecdysteroid receptor (EcR) constitutively expressed in vertebrate cells varies depending on the isoforms. Besides ligand binding and heterodimerization with ultraspiracle (USP), which stabilizes receptor protein concentration, degradation is regulated by interaction of the receptor complex with different ecdysteroid response elements (EcREs). Coexpression of EcREs significantly reduces ecdysteroid receptor concentration depending on the type of EcRE. Transcriptional activity and interaction with hormone response elements (HREs) as determined by Electrophoretic Mobility Shift Assay (EMSA) are often inversely related to receptor protein concentration. The complex regulation of receptor protein concentration offers an additional opportunity to regulate transcriptional activity in an isoform- and target cell-specific manner and allows the temporal limitation of hormone action.
核受体的转录活性是转激活能力和受体蛋白浓度的结果。脊椎动物细胞中组成型表达的蜕皮激素受体 (EcR) 的浓度取决于同工型。除了与超螺甾（USP）结合配体和异二聚化，这稳定了受体蛋白浓度外，降解还受受体复合物与不同蜕皮激素反应元件 (EcRE) 的相互作用调节。EcRE 的共表达根据 EcRE 的类型显著降低蜕皮激素受体浓度。通过电泳迁移率变动分析 (EMSA) 测定的转录活性和与激素反应元件 (HRE) 的相互作用通常与受体蛋白浓度呈负相关。受体蛋白浓度的复杂调节为以同工型和靶细胞特异性方式调节转录活性提供了另一种机会，并允许激素作用的时间限制。
