Enables guanyl-nucleotide exchange factor activity and small GTPase binding activity. Involved in several processes, including dendritic spine morphogenesis; marginal zone B cell differentiation; and positive regulation of GTPase activity. Located in dendritic spine. Is expressed in several structures, including central nervous system; endocrine gland; retina; thymus primordium; and trigeminal nerve. Orthologous to human DOCK10 (dedicator of cytokinesis 10). [provided by Alliance of Genome Resources, Apr 2022]