Sorting Motifs Involved in the Trafficking and Localization of the PIN1 Auxin Efflux Carrier

作者：Gloria Sáncho-Andrés, Esther Soriano‐Ortega, Caiji Gao, Joan Miquel Bernabé‐Orts, Madhumitha Narasimhan, Anna Ophelia Müller, Ricardo Tejos, Liwen Jiang, Jiřı́ Friml, Fernando Aniento, María Jesús Marcote · 发表于：PLANT PHYSIOLOGY · 年份：2016 · DOI：10.1104/pp.16.00373 · 被引用次数：27 · 研究领域：Plant Molecular Biology Research、Plant Reproductive Biology、Plant nutrient uptake and metabolism

In contrast with the wealth of recent reports about the function of μ-adaptins and clathrin adaptor protein (AP) complexes, there is very little information about the motifs that determine the sorting of membrane proteins within clathrin-coated vesicles in plants. Here, we investigated putative sorting signals in the large cytosolic loop of the Arabidopsis (Arabidopsis thaliana) PIN-FORMED1 (PIN1) auxin transporter, which are involved in binding μ-adaptins and thus in PIN1 trafficking and localization. We found that Phe-165 and Tyr-280, Tyr-328, and Tyr-394 are involved in the binding of different μ-adaptins in vitro. However, only Phe-165, which binds μA(μ2)- and μD(μ3)-adaptin, was found to be essential for PIN1 trafficking and localization in vivo. The PIN1:GFP-F165A mutant showed reduced endocytosis but also localized to intracellular structures containing several layers of membranes and endoplasmic reticulum (ER) markers, suggesting that they correspond to ER or ER-derived membranes. While PIN1:GFP localized normally in a μA (μ2)-adaptin mutant, it accumulated in big intracellular structures containing LysoTracker in a μD (μ3)-adaptin mutant, consistent with previous results obtained with mutants of other subunits of the AP-3 complex. Our data suggest that Phe-165, through the binding of μA (μ2)- and μD (μ3)-adaptin, is important for PIN1 endocytosis and for PIN1 trafficking along the secretory pathway, respectively.