RAB GTPase Binding Effector Protein 2 (RABEP2)

Using a yeast 2-hybrid system, Gournier et al. (1998) identified a novel rat gene, which they called rabaptin-5-beta, encoding a 62-kD protein that interacts with the GTP-bound form of RAB5, a small GTPase involved in signal transduction and mitogenesis. The deduced protein, RABEP2, shares 42% sequence identity with rat RABEP1. Both proteins contain coiled-coil repeats and are recruited on the endosomal membrane by RAB5 in the presence of GTP.Gournier et al. (1998) found that RABEP2 does not form heterodimers with RABEP1 but does complex with RAB guanine nucleotide exchange factor-1 (RABGEF1). Immunodepletion with an antibody against the RABEP2 complex resulted in partial inhibition of early endosome fusion.