(A) Diagram of Sd protein and deletion constructs. The TEA DNA binding domain is between aa 85–155. (B) S2 cells were transfected with the indicated Yki and Sd constructs, followed by immunoprecipitation and western blot analyses with the indicated antibodies. Arrows indicate IgG. (C) Diagram of the 3XSd2-luc reporter gene. Three copies of a DNA fragment containing tandem Sd binding sites (shaded sequence) from the dSRF enhancer (dSRF-A2-I) were placed upstream of the heat shock basal promoter (hs) followed by the luciferase coding sequence. (D) Sd and Yki act synergistically to activate the 3XSd2-luc reporter gene. S2 cells were transfected by the indicated Yki and Sd expression constructs plus the luciferase reporter gene, followed by the dual luciferase assay. F, N, and C indicate the full-length Sd, Sd-N, and Sd-C, respectively.