BiFC analysis of the HX requirement for Hox-Exd interactions in the Drosophila embryo.
(A) Scheme of Hox and Exd fusion proteins used as UAS constructs for BiFC analysis in the Drosophila embryo. The place of the HX with regard to the Homeodomain (HD) is to scale for each Hox protein. The HX mutation engineered in each Hox protein is indicated, as well as the HD mutation in Exd. VC and VN correspond to the C-terminal and N-terminal fragments of the Venus fluorescent protein, respectively. (B–C) Images are illustrative confocal captures of stage 10 living embryos. Each lane corresponds to a different Hox protein, whose fusion variants are expressed with a specific Gal4 driver, as indicated on the left. First and second columns correspond to BiFC between Hox and the wild type or HD-mutated form of Exd, respectively. The third column corresponds to BiFC between Exd and the HX-mutated Hox proteins. Panels on the right show the statistical quantification, as a boxplot representation, of fluorescent signals resulting from BiFC in each condition (see also Materials and Methods). Quantifications with mutated Exd and Hox proteins are numbered and are represented as a percentage of the BiFC normally obtained with the corresponding wild type proteins. Dotted-white boxes in (B) indicate the zone where BiFC signals have been quantified. See also Figures S1, S2, S3, S4.