title: Conserved function of the lysine-based KXD/E motif in Golgi retention for endomembrane proteins among different organisms.
abstract: We recently identified a new COPI-interacting KXD/E motif in the C-terminal cytosolic tail (CT) of Arabidopsis endomembrane protein 12 (AtEMP12) as being a crucial Golgi retention mechanism for AtEMP12. This KXD/E motif is conserved in CTs of all EMPs found in plants, yeast, and humans and is also present in hundreds of other membrane proteins. Here, by cloning selective EMP isoforms from plants, yeast, and mammals, we study the localizations of EMPs in different expression systems, since there are contradictory reports on the localizations of EMPs. We show that the N-terminal and C-terminal GFP-tagged EMP fusions are localized to Golgi and post-Golgi compartments, respectively, in plant, yeast, and mammalian cells. In vitro pull-down assay further proves the interaction of the KXD/E motif with COPI coatomer in yeast. COPI loss of function in yeast and plants causes mislocalization of EMPs or KXD/E motif-containing proteins to vacuole. Ultrastructural studies further show that RNA interference (RNAi) knockdown of coatomer expression in transgenic Arabidopsis plants causes severe morphological changes in the Golgi. Taken together, our results demonstrate that N-terminal GFP fusions reflect the real localization of EMPs, and KXD/E is a conserved motif in COPI interaction and Golgi retention in eukaryotes.
authors.affiliation: Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, and.
authors.forename: Cheuk Hang
authors.initials: CH
authors.lastname: Woo
authors.affiliation: Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, and.
authors.forename: Caiji
authors.initials: C
authors.lastname: Gao
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Yu
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Linna
authors.initials: L
authors.lastname: Tu
authors.affiliation: School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Zhaoyue
authors.initials: Z
authors.lastname: Meng
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: David K
authors.initials: DK
authors.lastname: Banfield
authors.affiliation: School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Yao
authors.affiliation: Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, and CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China ljiang@cuhk.edu.hk).
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D022181:COP-Coated Vesicles / Q000378:metabolism*; D017124:Conserved Sequence; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D042541:Intracellular Space; D008239:Lysine / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D013329:Structure-Activity Relationship; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D008239:Lysine