The vacuolar transport of aleurain-GFP and 2S albumin-GFP fusions is mediated by the same pre-vacuolar compartments in tobacco BY-2 and Arabidopsis suspension cultured cells

Authors

  • Yansong Miao,

    1. Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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  • Kwun Yee Li,

    1. Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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  • Hong-Ye Li,

    1. Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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  • Xiaoqiang Yao,

    1. Department of Physiology, School of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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  • Liwen Jiang

    Corresponding author
    1. Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
      (fax +852 2603 5646; e-mail: ljiang@cuhk.edu.hk).
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(fax +852 2603 5646; e-mail: ljiang@cuhk.edu.hk).

Summary

Soluble proteins reach vacuoles because they contain vacuolar sorting determinants (VSDs) that are recognized by vacuolar sorting receptor (VSR) proteins. Pre-vacuolar compartments (PVCs), defined by VSRs and GFP-VSR reporters in tobacco BY-2 cells, are membrane-bound intermediate organelles that mediate protein traffic from the Golgi apparatus to the vacuole in plant cells. Multiple pathways have been demonstrated to be responsible for vacuolar transport of lytic enzymes and storage proteins to the lytic vacuole (LV) and the protein storage vacuole (PSV), respectively. However, the nature of PVCs for LV and PSV pathways remains unclear. Here, we used two fluorescent reporters, aleurain-GFP and 2S albumin-GFP, that represent traffic of lytic enzymes and storage proteins to LV and PSV, respectively, to study the PVC-mediated transport pathways via transient expression in suspension cultured cells. We demonstrated that the vacuolar transport of aleurain-GFP and 2S albumin-GFP was mediated by the same PVC populations in both tobacco BY-2 and Arabidopsis suspension cultured cells. These PVCs were defined by the seven GFP-AtVSR reporters. In wortmannin-treated cells, the vacuolated PVCs contained the mRFP-AtVSR reporter in their limiting membranes, whereas the soluble aleurain-GFP or 2S albumin-GFP remained in the lumen of the PVCs, indicating a possible in vivo relationship between receptor and cargo within PVCs.

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