Enables guanyl-nucleotide exchange factor activity and small GTPase binding activity. Involved in endocytic recycling; positive regulation of GTPase activity; and positive regulation of immune response. Predicted to be located in cytoplasmic vesicle. Predicted to be active in cytosol and nuclear speck. Orthologous to human DENND1B (DENN domain containing 1B). [provided by Alliance of Genome Resources, Apr 2022]