Enables guanyl-nucleotide exchange factor activity. Predicted to be involved in regulation of ARF protein signal transduction. Predicted to act upstream of or within ARF protein signal transduction. Located in ruffle membrane. Is expressed in several structures, including brain; eye; genitourinary system; hemolymphoid system gland; and liver. Orthologous to human PSD3 (pleckstrin and Sec7 domain containing 3). [provided by Alliance of Genome Resources, Apr 2022]