Abstract
In animal cells, RAB5 GTPase is known as a molecular switch regulating various aspects of endosomal functions including membrane fusion, motility, and alteration of lipid composition. RAB5 fulfills these diverse functions through interactions with various effector molecules. In Arabidopsis thaliana, there are two conventional type of RAB5 members, ARA7 and RHA1. ara7 rha1 double mutants show gametophytic lethality, which indicates their redundant but essential function. The signal from plant RAB5s could also be mediated via effector molecules to induce downstream reactions, but no such effectors have been identified thus far. We looked for effectors of A. thaliana RAB5s by a yeast two-hybrid method. As a result, we succeeded in isolation of one candidate whose subcellular localization was changed depending on the nucleotide state of ARA7. The close relationship between the candidate and plant RAB5s was also supported by genetic studies. Surprisingly, the effector candidate also interacted with the other endosomal RAB. In this meeting, we will report results of biochemical and genetic studies on the effector candidate.
