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AtUTr1 a UDP‐galactose/UDP‐glucose transporter from Arabidopsis thaliana is located at the endoplasmic reticulum and is involved in protein folding quality control
Author(s) -
Orellana Ariel,
Reyes Francisca,
Marchant Lorena,
Norambuena Lorena,
Nilo Ricardo,
Silva Herman
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a55-c
Subject(s) - endoplasmic reticulum , unfolded protein response , arabidopsis thaliana , protein folding , microbiology and biotechnology , glycoprotein , biochemistry , cytosol , chemistry , transporter , mutant , biology , enzyme , gene
The folding of glycoproteins in the endoplasmic reticulum depends on quality control mechanism. During this process, a continuous trimming and UDP‐glucose‐dependent re‐glucosylation of misfolded glycoproteins takes place. The re‐glucosylation is catalyzed by an ER lumenal enzyme that uses UDP‐glucose as substrate that has to be transported from the cytosol, however, until now, no UDP‐glucose transporter linked to this process has been yet described. When cells are exposed to stress, malfolded proteins are accumulated in the ER, triggering Unfolding Protein Response. This process leads to an up‐regulation in the expression of genes involved in quality control. Here, we provide evidence that AtUTr1, a UDP‐galactose/glucose transporter from Arabidopsis thaliana responds to stimuli that trigger unfolded protein response, increasing both the mRNA expression and the protein content. Moreover, two different approaches suggest that AtUTr1 is located at the ER. Finally we reasoned that an impairment in AtUTr1 should affect the re‐glucosylation of glycoproteins, resulting in an increase of malfolded protein that should trigger unfolded protein response. To test this hypothesis, we analyzed an AtUTr1 insertional mutant and found an up‐regulation of ER chaperones, suggesting that these plants have a constitutive activation of unfolded protein response. Supported by: Fondecyt 1030551, MNPCB P02‐009‐F