Ras effector protein. May function as an upstream activator and/or downstream effector for RAB5B in endocytic pathway. May function as a guanine nucleotide exchange (GEF) of RAB5B, required for activating the RAB5 proteins by exchanging bound GDP for free GTP (By similarity). Homotetramer; probably composed of anti-parallel linkage of two parallel dimers. Interacts with Ras. Interacts with RAB5B, with a much higher affinity for GTP-bound activated RAB5B. Does not interact with other members of the Rab family (By similarity). Belongs to the RIN (Ras interaction/interference) family. Contaminating sequence. Sequence of unknown origin in the N-terminal part. Contaminating sequence. Sequence of unknown origin in the N-terminal part. Contaminating sequence. Sequence of unknown origin in the N-terminal part. Contaminating sequence. Sequence of unknown origin in the N-terminal part.