Enables guanyl-nucleotide exchange factor activity and inositol 1,4,5 trisphosphate binding activity. Involved in dendrite morphogenesis and endosome organization. Located in several cellular components, including bicellular tight junction; cell body; and endosome. Part of BLOC-1 complex. Is active in cytoplasm; dendritic shaft; and dendritic spine. Is expressed in brain and spinal cord. Orthologous to human CYTH2 (cytohesin 2). [provided by Alliance of Genome Resources, Apr 2022]