title: The Golgi localization of Arabidopsis thaliana beta1,2-xylosyltransferase in plant cells is dependent on its cytoplasmic and transmembrane sequences.
abstract: To investigate the targeting of proteins to the plant Golgi we studied Arabidopsis thaliana beta1,2-xylosyltransferase (XylT), a glycosyltransferase which is unique to plants and some invertebrates. Different deletion constructs of the putative cytoplasmic (C)-transmembrane (T)-stem (S) region of the enzyme were transiently expressed in the tobacco-related model plant species Nicotiana benthamiana. Subcellular localization of fusion proteins between CTS, CT, T, or C domains and the reporter molecule green fluorescent protein by fluorescence microcopy and density-gradient centrifugation revealed that the CT region alone is sufficient to sustain Golgi retention of XylT without the contribution of any luminal sequences. The finding of an incomplete retention by the T region alone suggests an important auxiliary role of the C domain in Golgi retention of the protein. However, the C segment did not confer any Golgi retention by itself, as the respective fusion protein was found exclusively in the cytoplasm. These results provide evidence that plant and mammalian cells rely on similar mechanisms to deliver glycosyltransferases to the Golgi apparatus.
authors.affiliation: Zentrum für Angewandte Genetik, Universität für Bodenkultur Wien, Austria.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Dirnberger
authors.forename: Peter
authors.initials: P
authors.lastname: Bencúr
authors.forename: Lukas
authors.initials: L
authors.lastname: Mach
authors.forename: Herta
authors.initials: H
authors.lastname: Steinkellner
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D018506:Gene Expression Regulation, Plant; D006056:Golgi Apparatus / Q000201:enzymology*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D010430:Pentosyltransferases; C408586:beta 1,2-xylosyltransferase