Fig. 7. Identification of a chromodomain protein interacting with Z4. (A) Proteins were immunoprecipitated from nuclear extracts prepared from Kc cells with the anti-Z4 antibody, resolved by SDS-PAGE on a 8% gel and visualized by Coomassie staining. The major band at a relative molecular weight of 150-160 kDa was eluted from the gel and analyzed by MALDI mass spectrometry. The band labeled Chriz is the protein encoded by the gene CG10712. (B-D) Polytene chromosomes of a transgenic line that expressed a myc-tagged Chriz protein in salivary glands were stained with an antibody against the myc-tag. The DNA staining (blue) is complementary to the staining of myc-Chriz (red), showing its interband localization on all chromosomes (A). myc-Chriz is restricted to the euchromatic parts of the chromosomes and does not bind to the heterochromatic chromocentre (C). At higher resolution the localization of myc-Chriz to a high number of interbands is obvious from the optical section shown in (D). It is identical to the interband localization of Z4.