title: The C-terminal extension of a hybrid immunoglobulin A/G heavy chain is responsible for its Golgi-mediated sorting to the vacuole.
abstract: We have assessed the ability of the plant secretory pathway to handle the expression of complex heterologous proteins by investigating the fate of a hybrid immunoglobulin A/G in tobacco cells. Although plant cells can express large amounts of the antibody, a relevant proportion is normally lost to vacuolar sorting and degradation. Here we show that the synthesis of high amounts of IgA/G does not impose stress on the plant secretory pathway. Plant cells can assemble antibody chains with high efficiency and vacuolar transport occurs only after the assembled immunoglobulins have traveled through the Golgi complex. We prove that vacuolar delivery of IgA/G depends on the presence of a cryptic sorting signal in the tailpiece of the IgA/G heavy chain. We also show that unassembled light chains are efficiently secreted as monomers by the plant secretory pathway.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Hadlington
authors.forename: Aniello
authors.initials: A
authors.lastname: Santoro
authors.forename: James
authors.initials: J
authors.lastname: Nuttall
authors.forename: Jürgen
authors.initials: J
authors.lastname: Denecke
authors.forename: Julian K-C
authors.initials: JK
authors.lastname: Ma
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vitale
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Frigerio
mesh_terms: D000818:Animals; D006056:Golgi Apparatus / Q000378:metabolism*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D007147:Immunoglobulin Light Chains / Q000378:metabolism; D021382:Protein Sorting Signals / Q000235:genetics / Q000502:physiology*; D011523:Protoplasts / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism; D014162:Transfection; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D021382:Protein Sorting Signals