ArabidopsisµA-adaptin interacts with the tyrosine motif of the vacuolar sorting receptor VSR-PS1

In receptor-mediated transport pathways in mammalian cells, clathrin-coated vesicle (CCV) µ-adaptins are the main binding partners for the tyrosine sorting/internalization motif (YXXØ). We have analyzed the function of the µA-adaptin, one of the five µ-adaptins from Arabidopsis thaliana, by pull-down assays and plasmon resonance measurements using its receptor-binding domain (RBD) fused to a histidine tag. We show that this adaptin is able to bind the consensus tyrosine motif YXXØ from the pea vacuolar sorting receptor (VSR)-PS1, as well as from the mammalian trans-Golgi network (TGN)38 protein. Moreover, the tyrosine residue was revealed to be crucial for binding of the complete cytoplasmic tail of VSR-PS1 to the plant µA-adaptin. The trans-Golgi localization of the µA-adaptin strongly suggests its involvement in Golgi- to vacuole-trafficking events.