Identification and characterization of AtCASP, a plant transmembrane Golgi matrix protein.
Golgins are a family of coiled-coil proteins that are associated with the Golgi apparatus. They are necessary for tethering events in membrane fusion and may act as structural support for Golgi cisternae. Here we report on the identification of an Arabidopsis golgin which is a homologue of CASP, a known transmembrane mammalian and yeast golgin. Similar to its homologues, the plant CASP contains a long N-terminal coiled-coil region protruding into the cytosol and a C-terminal transmembrane domain with amino acid residues which are highly conserved across species. Through fluorescent protein tagging experiments, we show that plant CASP localizes at the plant Golgi apparatus and that the C-terminus of this protein is sufficient for its localization, as has been shown for its mammalian counterpart. In addition, we demonstrate that the plant CASP is able to localize at the mammalian Golgi apparatus. However, mutagenesis of a conserved tyrosine in the transmembrane domain revealed that it is necessary for ER export and Golgi localization of the Arabidopsis CASP in mammalian cells, but is not required for its correct localization in plant cells. These data suggest that mammalian and plant cells have different mechanisms for concentrating CASP in the Golgi apparatus.
Renna
Luciana
L
Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada.
Hanton
Sally L
SL
Stefano
Giovanni
G
Bortolotti
Lauren
L
Misra
Vikram
V
Brandizzi
Federica
F
D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002522:Chlorocebus aethiops; D006056:Golgi Apparatus / Q000378:metabolism*; D000077614:Golgi Matrix Proteins; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000166:cytology / Q000235:genetics; D014162:Transfection; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism; D014709:Vero Cells
D029681:Arabidopsis Proteins; C504617:CASP protein, Arabidopsis; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D014443:Tyrosine