Enables GTPase activator activity. Involved in macropinocytosis; myeloid dendritic cell activation involved in immune response; and positive regulation of phagocytosis. Acts upstream of or within several processes, including T cell activation; immunological synapse formation; and membrane raft polarization. Predicted to be located in cytoplasm; cytoskeleton; and membrane. Is expressed in central nervous system; paraxial mesenchyme; and retina. Human ortholog(s) of this gene implicated in immunodeficiency 40. Orthologous to human DOCK2 (dedicator of cytokinesis 2). [provided by Alliance of Genome Resources, Apr 2022]