Contribution of p50/DM self-association to its binding to other dynactin subunits. A, HeLa cell lysates (right panels) were incubated with equal amounts of wild type or deleted GST-hDM fusions (lower left panel, Ponceau red) immobilized on GSH-Sepharose beads. Bound proteins were analyzed by Western blot with anti-p150, -p62, and -Arp1 antibodies. B, lysate from 293T cells expressing HA-tagged p24 (lower right panel) was incubated with equal amounts of the purified wild type or deleted GST-hDM fusions (upper panel, Ponceau red) immobilized on GSH-Sepharose beads. Bound proteins were analyzed by Western blot with anti-HA mAb (lower left panel).