Targeting mechanisms of secretory carrier membrane protein 1 in tobacco BY-2 cells.

• Other Authors: Cai, Yi
• Format: Others
• Language: English; Chinese
• Published: 2010
• Subjects: Biological transport; Membrane proteins; Plant proteins; Tobacco > Cytology; Membrane Proteins; Plant Proteins; Protein Transport; Tobacco > cytology
• Online Access: http://library.cuhk.edu.hk/record=b6075074; http://repository.lib.cuhk.edu.hk/en/item/cuhk-344707

Brefeldin A (BFA) has been a useful tool for studying organelle dynamics and protein trafficking in plant cells. Using several Golgi (MAN1 and GONST1) and TGN (SCAMP1 and SYP61) fluorescent protein markers as tools, I have showed that BFA-induced aggregates from Golgi apparatus and TGN are morphologically distinct in the same plant cells. In addition, the internalized endosomal marker FM4-64 colocalized with the TGN-derived aggregates but separated from the Golgi aggregates. In the presence of the endocytosis inhibitor tyrphostin A23, SCAMP1 and FM4-64 are largely excluded from the TGN SYP61-positive BFA-induced aggregates, indicating homotypic fusion of TGN rather than de novo endocytic trafficking is important for the formation of TGN/EE-derived BFA-induced aggregates. Since the TGN also serves as an EE receiving materials from plasma membrane continuously, these data therefore support the notion that the secretory Golgi organelle is distinct from the endocytic TGN/EE in response to BFA treatment in plant cells. === Little is known about the trafficking mechanism of plasma membrane (PM) proteins in the endomembrane system of plant cells that contain several membrane-bound organelles including the endoplasmic reticulum (ER), Golgi, trans-Golgi network (TGN) of early endosome (EE), prevacuolar compartment (PVC) or late endosome (LE). Here, I study the transport pathway and sorting signals of secretory carrier membrane protein 1 (SCAMP1) by following its transient expression in tobacco BY-2 protoplasts and show that SCAMP1 reaches the PM via an ER-Golgi-TGN-PM pathway. Loss-of-function and gain-of-function analysis of various GFP fusions with SCAMP1 mutations further demonstrates that: (1) the cytosolic N terminus of SCAMP1 contains an ER export signal; (2) the transmembrane domain 2 (TMD2) and TMD3 of SCAMP1 are essential for Golgi export; and (3) SCAMP1 TMD1 is essential for TGN-to-PM targeting. Therefore, both the cytosolic N-terminus and TMD sequences of SCAMP1 play integral roles in mediating its transport to the PM via an ER-Golgi-TGN pathway. === Cai, Yi. === Adviser: Liwen Jiang. === Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . === Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. === Includes bibliographical references (leaves 93-102). === Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. === Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. === Abstract also in Chinese.