title: The trafficking pathway of a wheat storage protein in transgenic rice endosperm.
abstract: OBJECTIVE
  The trafficking of proteins in the endoplasmic reticulum (ER) of plant cells is a topic of considerable interest since this organelle serves as an entry point for proteins destined for other organelles, as well as for the ER itself. In the current work, transgenic rice was used to study the pattern and pathway of deposition of the wheat high molecular weight (HMW) glutenin sub-unit (GS) 1Dx5 within the rice endosperm using specific antibodies to determine whether it is deposited in the same or different protein bodies from the rice storage proteins, and whether it is located in the same or separate phases within these.
  
  
  METHODS
  The protein distribution and the expression pattern of HMW sub-unit 1Dx5 in transgenic rice endosperm at different stages of development were determined using light and electron microscopy after labelling with antibodies.
  
  
  RESULTS
  The use of HMW-GS-specific antibodies showed that sub-unit 1Dx5 was expressed mainly in the sub-aleurone cells of the endosperm and that it was deposited in both types of protein body present in the rice endosperm: derived from the ER and containing prolamins, and derived from the vacuole and containing glutelins. In addition, new types of protein bodies were also formed within the endosperm cells.
  
  
  CONCLUSIONS
  The results suggest that the HMW 1Dx5 protein could be trafficked by either the ER or vacuolar pathway, possibly depending on the stage of development, and that its accumulation in the rice endosperm could compromise the structural integrity of protein bodies and their segregation into two distinct populations in the mature endosperm.
authors.affiliation: Department of Plant Physiology and Molecular Plant Biology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Maria
authors.initials: M
authors.lastname: Oszvald
authors.forename: Laszlo
authors.initials: L
authors.lastname: Tamas
authors.forename: Peter R
authors.initials: PR
authors.lastname: Shewry
authors.forename: Paola
authors.initials: P
authors.lastname: Tosi
mesh_terms: D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D056625:Endosperm / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D005983:Glutens / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009928:Organ Specificity; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D021381:Protein Transport; D014908:Triticum / Q000235:genetics*; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D005983:Glutens; C037302:glutenin
keywords: HMW-GS; Oryza sativa; Triticum aestivum; cereal endosperm; immunolocalization; protein bodies; protein trafficking; transgenic rice; wheat