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Thereafter the posttranslational modified antibodies are packaged into secretory vesicles, which are directed to the cytoplasmic membrane where they fuse with the membrane leading to the release of the antibodies. However, the exact mechanism of the transport to the plasma membrane via secretory vesicles in plants is not yet well characterized. | Thereafter the posttranslational modified antibodies are packaged into secretory vesicles, which are directed to the cytoplasmic membrane where they fuse with the membrane leading to the release of the antibodies. However, the exact mechanism of the transport to the plasma membrane via secretory vesicles in plants is not yet well characterized. | ||
+ | Mechanisms of regulated unconventional protein secretion, Nickel and Rabouille, 2009, Nature | ||
+ | Organization of the ER-Golgi interface for membrane traffic control, Brandizzi and Barlowe, 2013, Nature | ||
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Revision as of 17:17, 28 October 2013
PHAECTORY: Phaeodactylum tricornutum
Antibody secretion in PHAECTORY
We challenged PHAECTORY as a green system for the production of antibodies which are directly secreted into the pure surrounding medium. The secretion of the antibodies is mediated via the regulated secretory pathway. Antibodies or other substances like hormones or neurotransmitter are translated into the ER and afterwards transported to the plasma membrane via the trans Golgi network.
The genes for the Hepatitis B antibody produced in PHAECTORY are encoded by the nuclear genome where transcription takes place. The produced messenger RNA of the Hepatitis B antibody contains an amino terminal signal peptide which is recognized and bound through a signal peptide recognition particle. Posttranslational modifications like the removal of the signal peptide through a signal peptidase are initially performed in the ER.
The antibodies enter the ER as nascent proteins and are folded in the ER lumen with the aid of chaperones. Before the full assembled antibodies leave the ER the N-glycosylation is conducted. Afterwards the antibodies are transported (anterograde traffic) to the Golgi apparatus via COP (coat protein complex) II vesicles. Therefore the proteins exit the ER via ER exit sites and are packaged into COPII coated vesicles which perform vesicle budding. The COPII carrier shuttles the cargo from the ER to the Golgi network driven by motor proteins along the cytoskeleton in the cell. Reaching the Golgi network the v-SNAREs of the COPII vesicles bind to the t-SNAREs of the Golgi leading to a fusion. The antibodies enter the Golgi apparatus which consists of several cisterns (cis, medial and trans). Additional posttranslational modifications like the O-glycosylation and the further processing of the sugar chains from the ER are executed in the Golgi apparatus before leaving the compartment.
Thereafter the posttranslational modified antibodies are packaged into secretory vesicles, which are directed to the cytoplasmic membrane where they fuse with the membrane leading to the release of the antibodies. However, the exact mechanism of the transport to the plasma membrane via secretory vesicles in plants is not yet well characterized.
Mechanisms of regulated unconventional protein secretion, Nickel and Rabouille, 2009, Nature Organization of the ER-Golgi interface for membrane traffic control, Brandizzi and Barlowe, 2013, Nature