Figure 1.

Protein components of the gypsy insulator are present in the nuclear matrix. A collection of Drosophila 6–18-h-old embryos was subjected to a karyoskeletal or nuclear matrix fractionation procedure, and equal amounts of the fractions were run on 7.5 and 10% polyacrylamide gels and subjected to Western blot analysis using antibodies to Mod(mdg4), Su(Hw), lamin, histone H3, and Ubx. Antibodies against Mod(mdg4) were specific to the Mod(mdg4) 2.2 isoform, which is the isoform present in the gypsy insulator (Ghosh et al., 2001; Mongelard et al., 2002).