FIG. 3.

Formation of SAHF by ASF1a depends on histone H3-binding activity. (A) HA-tagged wild-type (WT) ASF1a or its mutants deficient in histone H3 binding were expressed in WI38 cells by retrovirus infection and drug selected with 3 μg/ml puromycin. Ten days postinfection, drug-selected cells were stained with DAPI and antibodies to macroH2A1.2. The white arrow marks the inactive X chromosome. (B) One hundred cells shown in panel A were scored for the indicated nuclear foci. The inactive X chromosome was excluded when scoring cells with macroH2A foci. The bottom panel shows whole-cell lysates Western blotted with anti-HA and antiactin antibodies.