FIG. 5.

roX2 is expressed in S2 cells and associates with the MSL proteins. (A) Northern analysis shows that both roX RNAs are expressed in adult Drosophila males (M) but not females (F); only roX2 was detected in S2 cells. The filters were reprobed for rp49 RNA as a loading control. (B) RNA was extracted from anti-MSL1 immunoprecipitates (M1) or the corresponding preimmune serum (PI) and subjected to RT-PCR. Agarose gel electrophoresis of PCR products and staining with ethidium bromide detected significant levels of roX2 RNA in the anti-MSL1 immunoprecipitates, while a lower level of roX2 RNA (1 to 2%) was detected in the preimmune serum. This level of contamination is consistent with the amount of contaminating MSL proteins observed in these immunoprecipitates (Fig. 4B). A kanamycin kinase transcript was used to monitor variation in processing of samples; comparable levels of this control RNA (Ctrl) were detected by RT-PCR in the preimmune and anti-MSL1 immunoprecipitates.