FIGURE 2.

The C-terminal region of Caudal is important for core promoter-preferential activation of ftz. Drosophila S2R+ cells were co-transfected with expression vectors for either full-length Drosophila Caudal or Caudal deletion constructs as well as with firefly luciferase reporter constructs driven by the ftz enhancer-promoter containing either an mTATA or mDPE motif. To normalize for variations in transfection efficiency, cells were co-transfected with a Pol III-Renilla luciferase control plasmid and assayed for Dual-Luciferase activity. The activities are reported relative to the promoters in the absence of a co-transfected Caudal expression plasmid, which were defined to be 1. A, schematic representation of the full-length FLAG-Caudal protein and the Caudal mutants harboring N-terminal or C-terminal deletions. The blue box at the N terminus of the Caudal expression constructs denotes a FLAG tag. B, transcriptional activation of the ftz reporter gene by the full-length FLAG-Caudal and N-terminal deletion constructs (n = 3). C, Western blot (WB) analysis of Caudal expression vectors in S2R+ cells. Equal amounts of total protein were subjected to Western blot analysis with anti-FLAG antibodies. Actin served as a loading control. The asterisk denotes a cross-reactive band. D, transcriptional activation of the ftz reporter gene by the full-length FLAG-Caudal and C-terminal deletion constructs (n = 3). In all panels, error bars represent S.E. ns, p > 0.05; **, 0.001 ≤ p ≤ 0.01; ***, p ≤ 0.001.