Plant RMR proteins: unique vacuolar sorting receptors that couple ligand sorting with membrane internalization

Authors

  • Hao Wang,

    1.  Department of Biology, Centre for Cell and Developmental Biology, Chinese University of Hong Kong, China
    2.  State (China) Key Laboratory for Agrobaiotechnology, The Chinese University of Hong Kong, China
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  • John C. Rogers,

    1.  Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
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  • Liwen Jiang

    1.  Department of Biology, Centre for Cell and Developmental Biology, Chinese University of Hong Kong, China
    2.  State (China) Key Laboratory for Agrobaiotechnology, The Chinese University of Hong Kong, China
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L. Jiang, State (China) Key Laboratory for Agrobaiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
Fax: +852 2603 5646
Tel: +852 2609 6388
E-mail: ljiang@cuhk.edu.hk

Abstract

In receptor-mediated sorting of soluble protein ligands in the endomembrane system of eukaryotic cells, three completely different receptor proteins for mammalian (mannose 6-phosphate receptor), yeast (Vps10p) and plant cells (vacuolar sorting receptor; VSR) have in common the features of pH-dependent ligand binding and receptor recycling. In striking contrast, the plant receptor homology-transmembrane-RING-H2 (RMR) proteins serve as sorting receptors to a separate type of vacuole, the protein storage vacuole, but do not recycle, and their trafficking pathway results in their internalization into the destination vacuole. Even though plant RMR proteins share high sequence similarity with the best-characterized mammalian PA-TM-RING family proteins, these two families of proteins appear to play distinctly different roles in plant and animal cells. Thus, this minireview focuses on this unique sorting mechanism and traffic of RMR proteins via dense vesicles in various plant cell types.

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