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The GRV2/RME‐8 protein of Arabidopsis functions in the late endocytic pathway and is required for vacuolar membrane flow
Author(s) -
Silady Rebecca A.,
Ehrhardt David W.,
Jackson Karen,
Faulkner Christine,
Oparka Karl,
Somerville Chris R.
Publication year - 2008
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03314.x
Subject(s) - endosome , microbiology and biotechnology , vacuole , endocytic cycle , endocytosis , wortmannin , biology , vacuolar protein sorting , arabidopsis , brefeldin a , arabidopsis thaliana , mutant , cytoplasm , biochemistry , signal transduction , intracellular , golgi apparatus , pi3k/akt/mtor pathway , receptor , gene , endoplasmic reticulum
Summary The gravitropism defective 2 ( grv2 ) mutants of Arabidopsis thaliana were previously characterized as exhibiting shoot agravitropism resulting from mutations in a homolog of the Caenorhabditis elegans RECEPTOR‐MEDIATED ENDOCYTOSIS‐8 ( RME‐8 ) gene, which is required in C. elegans for endocytosis. A fluorescent protein fusion to the GRV2 protein localized to endosomes in transgenic plants, and vacuolar morphology was altered in grv2 mutants. A defect in vacuolar membrane dynamics provides a mechanistic explanation for the gravitropic defect, and may also account for the presence of an enlarged vacuole in early embryos, together with a nutrient requirement during seedling establishment. The GRV2‐positive endosomes were sensitive to Wortmannin but not brefeldin A (BFA), consistent with GRV2 operating late in the endocytic pathway, prior to delivery of vesicles to the central vacuole. The specific enlargement of GRV2:YFP structures by Wortmannin, together with biochemical data showing that GRV2 co‐fractionates with pre‐vacuolar markers such as PEP12/SYP21, leads us to conclude that in plants GRV2/RME‐8 functions in vesicle trafficking from the multivesicular body/pre‐vacuolar compartment to the lytic vacuole.