FIG. 4.

MLE association with the MSL complex. Significant levels of MLE are detected with other MSLs when immunoprecipitations are performed under low-salt conditions (see Materials and Methods). MSL complexes were eluted from M2-Flag agarose and subjected to a second immunoprecipitation with anti-MSL1. (A) A silver-stained protein is visible between MSL1 and MSL2/MOF. Two concentrations (1× and 5×) of a stringently washed anti-MLE immunoprecipitate (IP) were loaded on the same gel; correlation between silver staining and Western staining intensities as well as comigration by SDS-PAGE, confirms that this band is MLE. (B) Comparison of low-salt (LS) and high-salt (HS) washing conditions reveals a salt-sensitive association of MLE with the other MSLs. As seen by Western analysis, significant levels of MLE are released from immunoprecipitates when incubated with high-salt buffers but not low-salt buffers; MSL1 levels are unaffected. A preimmune control (PI) was washed under low-salt conditions and reveals a low level of contaminating MSLs in these preparations.