Fig. 3.

Contribution of individual S/T-rich motifs to HIB binding and Ci repression. (A) Diagrams of CiGA and full-length Ci constructs, with wild-type and mutated HIB-binding sites indicated by bars and crosses, respectively. (B and C) ptc-luc reporter assays in S2 cells expressing indicated CiGA (B) or full-length Ci (C) constructs in the presence or absence of HIB coexpression. The y-axis represents normalized ptc-luc activity. (D and E) S2 cells were cotransfected with wild-type or mutant Myc-CiN (D) or HACi (E) constructs and Flag- (D) or Myc-tagged HIB (E). Cell lysates were subjected to Western blot analysis directly (Lower) or immunoprecipitation followed by Western blot analysis with indicated antibodies. Arrows and asterisks indicate pulled-down proteins and IgG, respectively.