Sebastien A. GauthierEric VanHaaftenLucy CherbasPeter CherbasRandall S. Hewes2016-01-082016-03-302016-01-082016-03-302012-08-09Gauthier SA, VanHaaften E, Cherbas L, Cherbas P, Hewes RS (2012) Cryptocephal, the Drosophila melanogaster ATF4, Is a Specific Coactivator for Ecdysone Receptor Isoform B2. PLoS Genetics 8(8): e1002883. doi:10.1371/journal.pgen.1002883http://hdl.handle.net/11244/23532We thank Yoonseung Park (Kansas State University) and Michael Adams (UC Riverside) for the ETH-GeneSwitch line, and David Durica, Lauren Evans, and Dahong Chen (University of Oklahoma) and Nancy Thompson (Indiana University) for technical assistance.Author Summary Nuclear receptors are proteins that regulate gene expression in response to steroid and thyroid hormones and other small lipid-soluble signaling molecules. In many cases, nuclear receptor genes encode multiple variants (isoforms) that direct tissue- and stage-specific hormonal responses. The sequence differences among isoforms are often found at the protein N-terminus, which mediates hormone-independent interactions with unknown regulatory partners to control target gene expression. Here, we show that the fruit fly Cryptocephal (CRC) protein is a specific coactivator for one of three isoforms of the receptor for the insect molting steroid, ecdysone. Our findings reveal a mechanism for differential activation of gene expression in response to ecdysone during insect molting and metamorphosis, and contribute to our understanding of isoform-specific functions of nuclear hormone receptors.en-USAttribution 3.0 United StatesLarvae,Molting,Basic leucine zipper domain,DNA-binding proteins,Drosophila melanogaster,Gene expression,DNA transcription,Transcription factorsResearch Article10.1371/journal.pgen.1002883false