Rab GTPases now comprise a family of >63 members. They are emerging as the key hub element controlling the membrane architecture of eukaryotic cells. They are intimately involved in vesicle targeting and fusion in both the endocytic and exocytic pathways and direct the assembly and disassembly of protein complexes that include regulators (GEFs and GAPs), effectors (tethers/motors) and fusion components (SNAREs) that control membrane targeting and...