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Signalling endosomes in plants: activated MAPKs associate with CCVs and endosomes |
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Wasser K,
Müller J, Preuss ML, Holstein S, Böhm N, Nielsen E, Hirt H, Menzel D, Šamaj
J |
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Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D – 53115 Bonn,
Germany |
| *email:
jozef.samaj@uni-bonn.de
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Mitogen-activated protein kinase (MAPK) pathways including ERK and p38
associate with signalling endosomes upon activation of growth factor receptors in mammalian cells. It is
believed that this scaffolding and compartmentalization of MAPK pathways is essential for achieving signal
specificity and more efficient transduction. In plants, almost nothing is known about targeting of MAPKs to
the endomembranes and to the cytoskeleton. We provide biochemical and cell biological evidence that two
Arabidopsis MAPKs, MPK4 and MPK6 are weakly associated with endosomes (later one also with CCVs) in
control cells. Additionally, three MAPKs, MPK3, 4 and 6 are associated in their activated state with endosomes
following diverse abiotic stresses. Active MPK4 and MPK6, but not MPK3, associate also with isolated
clathrin-coated vesicles (CCVs) upon biotic stress induced by elicitor (flagellin) treatment. These data
indicate a constitutive signalling from the endocytic compartment in plants. |
