title: Trafficking of the myrosinase-associated protein GLL23 requires NUC/MVP1/GOLD36/ERMO3 and the p24 protein CYB.
abstract: Proteins detrimental to endoplasmic reticulum (ER) morphology need to be efficiently exported. Here, we identify two mechanisms that control trafficking of Arabidopsis thalianaGLL23, a 43 kDa GDSL-like lipase implicated in glucosinolate metabolism through its association with the β-glucosidase myrosinase. Using immunofluorescence, we identified two mutants that showed aberrant accumulation of GLL23: large perinuclear ER aggregates in the nuclear cage (nuc) mutant; and small compartments contiguous with the peripheral ER in the cytoplasmic bodies (cyb) mutant. Live imaging of fluorescently tagged GLL23 confirmed its presence in the nuc and cyb compartments, but lack of fluorescent signals in the wild-type plants suggested that GLL23 is normally post-translationally modified for ER export. NUC encodes the MVP1/GOLD36/ERMO3 myrosinase-associated protein, previously shown to have vacuolar distribution. CYB is an ER and Golgi-localized p24 type I membrane protein component of coat protein complex (COP) vesicles, animal and yeast homologues of which are known to be involved in selective cargo sorting for ER-Golgi export. Without NUC, GLL23 accumulates in the ER this situation suggests that NUC is in fact active in the ER. Without CYB, both GLL23 and NUC were found to accumulate in cyb compartments, consistent with a role for NUC in GLL23 processing and indicated that GLL23 is the likely sorting target of the CYB p24 protein.
authors: Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors: Sylwia
authors: S
authors: Jancowski
authors: Amanda
authors: A
authors: Catching
authors: Jamie
authors: J
authors: Pighin
authors: Takamasa
authors: T
authors: Kudo
authors: Ilse
authors: I
authors: Foissner
authors: Geoffrey O
authors: GO
authors: Wasteneys
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D022181:COP-Coated Vesicles / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D006056:Golgi Apparatus / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D009154:Mutation; D021381:Protein Transport; D040901:Proteomics; D036226:Seedlings / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; C000592770:CYB protein, Arabidopsis; C580914:ERMO3 protein, Arabidopsis; D008565:Membrane Proteins; D002265:Carboxylic Ester Hydrolases; C000592769:GLL23 protein, Arabidopsis
keywords: Arabidopsis thaliana; GDSL-like lipase; coat protein complex; endoplasmic reticulum; glucosinolate metabolism; intracellular trafficking; myrosinase-associated protein; p24 protein