Guanine nucleotide exchange factor for the small GTPase RALA. May be involved in cytoskeleton organization. Interacts with the SH3 domains of GRB2, NCK1, PLCG1 and SRC. Associates with membranes through the PH domain. The PH domain mediates binding to membranes. It is required for efficient GEF activity. Truncated C-terminus.