A membrane trafficking pathway regulated by the plant-specific RAB GTPase ARA6.

Endosomal trafficking plays an integral role in various eukaryotic cell activities and serves as a basis for higher-order functions in multicellular organisms. An understanding of the importance of endosomal trafficking in plants is rapidly developing, but its molecular mechanism is mostly unknown. Several key regulators of endosomal trafficking, including RAB5, which regulates diverse endocytic events in animal cells, are highly conserved.

Vacuolar/pre-vacuolar compartment Qa-SNAREs VAM3/SYP22 and PEP12/SYP21 have interchangeable functions in Arabidopsis.

SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptors) mediate specific membrane fusion between transport vesicles or organelles and target membranes. VAM3/SYP22 and PEP12/SYP21 are Qa-SNAREs that act in the vacuolar transport pathway of Arabidopsis thaliana, and are localized predominantly on the vacuolar membrane and the pre-vacuolar compartment (PVC), respectively. Previous studies have shown that loss-of-function mutants of VAM3/SYP22 or PEP12/SYP21 showed male gametophytic lethality, suggesting that VAM3/SYP22 and PEP12/SYP21 possess different, non-redundant functions.

A SNARE complex unique to seed plants is required for protein storage vacuole biogenesis and seed development of Arabidopsis thaliana.

The SNARE complex is a key regulator of vesicular traffic, executing membrane fusion between transport vesicles or organelles and target membranes. A functional SNARE complex consists of four coiled-coil helical bundles, three of which are supplied by Q-SNAREs and another from an R-SNARE. Arabidopsis thaliana VAMP727 is an R-SNARE, with homologs only in seed plants.