Sorting Motifs Involved in the Trafficking and Localization of the PIN1 Auxin Efflux Carrier1
Phenylalanine 165 is important for PIN1 endocytosis and its trafficking through the secretory pathway. 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 sort...
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Published in | Plant physiology (Bethesda) Vol. 171; no. 3; pp. 1965 - 1982 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society of Plant Biologists
12.05.2016
|
Online Access | Get full text |
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Summary: | Phenylalanine 165 is important for PIN1 endocytosis and its trafficking through the secretory pathway.
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. |
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Bibliography: | www.plantphysiol.org/cgi/doi/10.1104/pp.16.00373 Present address: Centro de Biología Molecular Vegetal, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, 7800003 Ñuñoa, Santiago, Chile. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: María Jesús Marcote (mariajesus.marcote@uv.es). L.J., J.F., F.A., and M.J.M. designed the experiments; G.S.-A., E.S.-O., C.G., J.M.B.-O., M.N., A.M., and R.T. performed the experiments; F.A. and M.J.M. wrote the article, with inputs from J.F. and L.J. and comments from all other authors. |
ISSN: | 0032-0889 1532-2548 |
DOI: | 10.1104/pp.16.00373 |