function:Modulates cytoplasmic dynein binding to an organelle, and plays a role in prometaphase chromosome alignment and spindle organization during mitosis. May play a role in synapse formation during brain development.,similarity:Belongs to the dynactin subunit 2 family.,subunit:Subunit of dynactin, a multiprotein complex associated with dynein. Interacts with BICD2 (By similarity). Interacts with MAPRE1.,