Abstract
Unconventional protein secretion (UPS) describes secretion pathways that bypass one or several of the canonical secretion pit-stops on the way to the plasma membrane, and/or involve the secretion of leaderless proteins. So far, alternatives to conventional secretion were primarily observed and studied in yeast and animal cells. The sessile lifestyle of plants brings with it unique restraints on how they adapt to adverse conditions and environmental challenges. Recently, attention towards unconventional secretion pathways in plant cells has substantially increased, with the large number of leaderless proteins identified through proteomic studies. While UPS pathways in plants are certainly not yet exhaustively researched, an emerging notion is that induction of UPS pathways is correlated with pathogenesis and stress responses. Given the multitude UPS events observed, comprehensively organizing the routes proteins take to the apoplast in defined UPS categories is challenging. With the establishment of a larger collection of studied plant proteins taking these UPS pathways, a clearer picture of endomembrane trafficking as a whole will emerge. There are several novel enabling technologies, such as vesicle proteomics and chemical genomics, with great potential for dissecting secretion pathways, providing information about the cargo that travels along them and the conditions that induce them.
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Acknowledgements
This work was supported by the NSF-IOS-1258135 to G.D. and the Area of Excellence grant (AoE/M-05/12) from the Research Grants Council of Hong Kong to B.K.
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Davis, D.J., Kang, BH., Heringer, A.S., Wilkop, T.E., Drakakaki, G. (2016). Unconventional Protein Secretion in Plants. In: Pompa, A., De Marchis, F. (eds) Unconventional Protein Secretion. Methods in Molecular Biology, vol 1459. Humana Press, New York, NY. https://doi.org/10.1007/978-1-4939-3804-9_3
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