Rice SCAMP1 defines clathrin-coated, trans-golgi-located tubular-vesicular structures as an early endosome in tobacco BY-2 cells

Plant Cell. 2007 Jan;19(1):296-319. doi: 10.1105/tpc.106.045708. Epub 2007 Jan 5.


We recently identified multivesicular bodies (MVBs) as prevacuolar compartments (PVCs) in the secretory and endocytic pathways to the lytic vacuole in tobacco (Nicotiana tabacum) BY-2 cells. Secretory carrier membrane proteins (SCAMPs) are post-Golgi, integral membrane proteins mediating endocytosis in animal cells. To define the endocytic pathway in plants, we cloned the rice (Oryza sativa) homolog of animal SCAMP1 and generated transgenic tobacco BY-2 cells expressing yellow fluorescent protein (YFP)-SCAMP1 or SCAMP1-YFP fusions. Confocal immunofluorescence and immunogold electron microscopy studies demonstrated that YFP-SCAMP1 fusions and native SCAMP1 localize to the plasma membrane and mobile structures in the cytoplasm of transgenic BY-2 cells. Drug treatments and confocal immunofluorescence studies demonstrated that the punctate cytosolic organelles labeled by YFP-SCAMP1 or SCAMP1 were distinct from the Golgi apparatus and PVCs. SCAMP1-labeled organelles may represent an early endosome because the internalized endocytic markers FM4-64 and AM4-64 reached these organelles before PVCs. In addition, wortmannin caused the redistribution of SCAMP1 from the early endosomes to PVCs, probably as a result of fusions between the two compartments. Immunogold electron microscopy with high-pressure frozen/freeze-substituted samples identified the SCAMP1-positive organelles as tubular-vesicular structures at the trans-Golgi with clathrin coats. These early endosomal compartments resemble the previously described partially coated reticulum and trans-Golgi network in plant cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Androstadienes / pharmacology
  • Biomarkers
  • Brefeldin A / pharmacology
  • Cell Line
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure
  • Endosomes / metabolism*
  • Endosomes / ultrastructure
  • Golgi Apparatus / metabolism
  • Immunohistochemistry
  • Molecular Sequence Data
  • Nicotiana / genetics*
  • Nicotiana / ultrastructure
  • Organelles / classification
  • Organelles / ultrastructure
  • Oryza / genetics*
  • Plant Proteins / analysis*
  • Plant Proteins / chemistry
  • Plant Proteins / metabolism
  • Plants, Genetically Modified / drug effects
  • Plants, Genetically Modified / metabolism
  • Plants, Genetically Modified / ultrastructure
  • Pyridinium Compounds / analysis
  • Quaternary Ammonium Compounds / analysis
  • Recombinant Fusion Proteins / analysis
  • Sequence Alignment
  • Vesicular Transport Proteins / analysis*
  • Vesicular Transport Proteins / chemistry
  • Vesicular Transport Proteins / metabolism
  • Wortmannin


  • Androstadienes
  • Biomarkers
  • FM 4-64
  • Plant Proteins
  • Pyridinium Compounds
  • Quaternary Ammonium Compounds
  • Recombinant Fusion Proteins
  • Vesicular Transport Proteins
  • Brefeldin A
  • Wortmannin