Ras-related protein Rab9 is a member of the large Rab GTPase family. It is found in late endosomes, together with mannose 6-phosphate receptors (MPRs) and the tail-interacting protein of 47kDa (TIP47). Rab9 is a key mediator of vesicular transport from late endosomes to the trans-Golgi network (TGN) by redirecting the MPRs []. Rab9 has been identified as a key component for the replication of several viruses, including HIV1, Ebola, Marburg, and measles, making it a potential target for inhibiting a variety of viruses [].Rabs are regulated by GTPase activating proteins (GAPs), which interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins [, ].
