Plant vacuolar trafficking driven by RAB and SNARE proteins

• Two different trans-SNARE complexes mediate vacuolar trafficking pathways.
• RAB5 and RAB7 distinctly regulate endosomal/vacuolar trafficking pathways.
• The SAND–CCZ1 complex mediates RAB5-to-RAB7 conversion in vacuolar trafficking.
• The vacuolar trafficking pathway has uniquely diversified in plants.

Membrane-bounded organelles are connected to each other by membrane trafficking, which is accomplished by membrane fusion between transport vesicles and target organelles mediated by RAB GTPases and SNARE proteins. Of those trafficking pathways networking plant organelles, the vacuolar trafficking pathway has recently been shown to be uniquely diversified from non-plant systems, most likely reflecting unique functions of plant vacuoles such as the storage of proteins and other organic compounds, generation of turgor pressure, and space-filling to enlarge plant bodies. Plant-unique trafficking machineries in addition to evolutionarily conserved molecular components are allocated to this trafficking pathway in distinctive ways. In this review, we summarize recent findings on SNARE proteins and RAB GTPases mediating vacuolar transport in plants, especially focusing on the functions and regulation of two distinct trans-SNARE complexes and RAB5 and RAB7 in multiple vacuolar trafficking pathways.