Survey of nucleotide-specific Rab GTPase interactions reveals multiple Rab effectors.

Rab GTPases control myriad molecular functions by acting as a nucleotide-dependent switch for protein-protein interactions localized in discrete subcellular regions. Finding additional molecular roles for Rab GTPases depends on expanding the identification of their nucleotide-dependent interactions. Here we compare the interactome of Rab GTPases using a comprehensive large-scale yeast 2-hybrid approach powered by quantitative high-throughput sequencing, which was used to find interactions of the major mammalian Rab isoforms locked in a GDP or GTP conformation. These data showed an expanded set of interactions specific for GTP-bound Rab proteins, which many know Rab effectors shown capable of binding a wider repertoire of partners than previously appreciated. We also identified the RGS domain of Snx13 and Snx14 as a new Rab GTPase-binding domain that may bridge these ER-localized proteins with Rab5 and Rab11 endosomal compartments, respectively.