Figure 2.

In vivo UV crosslinking of zeste protein to the Uβ and Uβ Δ−200/−31 transgenes. (Upper) The endogenous Ubx gene, and the Uβ and Uβ Δ−200/−31 transgenes are diagrammed using the same conventions employed in Fig. 1D. The positions of the relevant XhoI (X), EcoRV (R), StuI (S), and PstI (P) restriction sites are shown. (Lower) Autoradiograms of Southern blots, which show the results of immunoprecipitation experiments with crosslinked chromatin isolated from Uβ or Uβ Δ−200/−31 transformant embryos (18). Two independent transformant lines of each construct were examined with the same result. Chromatin digested with StuI and EcoRV (proximal promoter) or with XhoI, EcoRV, and PstI (BXD element) was immunoprecipitated (IP) with affinity-purified anti-zeste antibody (+ antibody) or with anti-IgG antibody (− antibody). The coprecipitating DNA was then analyzed by Southern blot analysis. To allow quantitation, 0.005%, 0.002%, 0.0005%, 0.0002%, and 0.0001% of the total DNA (% Total) in the immunoprecipitation reaction is also shown. The restriction fragments from the endogenous Ubx gene and the transgenes are indicated. Note that the fragment derived from the proximal promoter of the Uβ Δ−200/−31 transgene is 169 base pairs smaller than the proximal promoter fragment of the Uβ transgene.