Fig. 1. A large complex involving Ptc, Smo and Sxl in Drosophila embryos. (A) Ci, Cos2, Ptc, Smo and Sxl immunoprecipitates from wild-type 0- to 12-hour embryonic extracts probed for Sxl, Ptc and Smo. Input lane (I) is 5% of extract used. The table gives the percentage of protein immunoprecipitated from an average of two or more experiments. (B) Fractionation of cytoplasmic extract from wild-type embryos analyzed by western blot using the antibodies in A as well as anti-Fu. Arrows at top show the elution position of the given size marker. Several of the Hh components are phosphorylated (asterisk) and migrate as doublets (Cos2 and Fu); Smo is also phosphorylated and does not migrate as a discrete band. `F' represents total extract from adult females used as a marker for each protein. Three arbitrary complex types of changing Hh components (Complex A-C) can be described. (C) Immunoprecipitation of fractions from each complex type with antibodies to known Hh components show that Ptc and other Hh components, as well as Sxl are associated. (D) Controls for immunoprecipitates of Hh complex components using antibodies to BicD, Dlg and Fz.