Functions as a guanine nucleotide exchange factor (GEF) activating either RalA or RalB GTPases and plays an important role in intracellular transport. Interacts and acts as an effector molecule for R-Ras, H-Ras, K-Ras, and Rap (By similarity). During bacterial clearance, recognizes 'Lys-33'-linked polyubiquitinated TRAF3 and subsequently mediates assembly of the exocyst complex (PubMed:27438768). {ECO:0000250|UniProtKB:Q03385, ECO:0000269|PubMed:27438768}. This is the function of Ensembl gene identifier ENSG00000160271 (RALGDS, ral guanine nucleotide dissociation stimulator).