Fig. 2.

Recombinant and endogenous HP1 interact with Hip using its chromo shadow domain. (A) GST pull-down experiments with a GST-Hip fusion protein or GST alone as a control and full-length and truncated His-tagged HP1 proteins were performed. (B) Eluted proteins were probed with anti-His antibody. Recombinant HP1-His protein migrates as two polypeptides of different sizes, which might be due to degradation. Full-length HP1 interacts with Hip and the HP1 chromo shadow domain (HP1-cs) but not the HP1 chromo domain (HP1-cd) or the hinge region (HP1-hinge). (C) Same conditions as in B, but this time nuclear extracts from larval salivary glands were used as a source of endogenous HP1 protein. (D) Anti-HP1 Western blot analysis after immunoprecipitation (IP) from salivary gland nuclear extracts with a combination of both anti-Hip antisera detected HP1 protein. Mock precipitation with preimmune sera did not retain HP1, indicating that Hip and HP1 interact in vivo.