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). Interacts with RIT1 and RIT2 (By similarity). Interacts with OOG1 (By similarity). Interacts with TRAF3 (PubMed:27438768). Interacts with HRAS (By similarity). Localizes mainly in the peripheral region of the cytoplasmic membrane in oocytes and in preimplantation embryos until the 8-cell stage. Between the late 1-cell and the early 2-cell stages, nuclear localization becomes stronger. After the 4-cell stage, not detected in the nucleus. The Ras-associating domain interacts with Ras. Phosphorylation of Tyr-814 by MET blocks HRAS binding.