VgEcR is a synthetic transcription factor that is a fusion of the ligand-binding and dimerization domain of the Drosophila ecdysone receptor, the DNA-binding domain of the GR, and the transcriptional activation domain of herpes simplex virus VP16. This gene expression system is designed to activate transcription upon dimerization of VgEcR with the retinoid X receptor (RXR), and binding of the heterodimer transactivates a synthetic ecdysone-responsive element (Saez et al. 2000).
