Modulates cytoplasmic dynein binding to an organelle, and plays a role in prometaphase chromosome alignment and spindle organization during mitosis. Involved in anchoring microtubules to centrosomes. May play a role in synapse formation during brain development. Subunit of dynactin, a multiprotein complex associated with dynein. Interacts with BICD2 and CEP135 (By similarity). Interacts with DYNAP (PubMed:20978158). Interacts with ECPAS (PubMed:20682791). Interacts with MAPRE1 (PubMed:10226031). Belongs to the dynactin subunit 2 family.