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Title: Molecular mechanisms regulating Golgi architecture during the mammalian cell division cycle
Author: Shorter, James Gordon
ISNI:       0000 0001 3407 4858
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2000
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During mammalian M phase vesicular transport ceases and the stacked Golgi ribbon is converted into a disseminated array of tubulovesicular clusters, as part of the process that ensures Golgi inheritance through successive generations. At telophase these tubulovesicular clusters are remodelled to regenerate the Golgi stack. In this thesis, an established cell free system that recreates many of these events has been used to probe the molecular workings of this process. During disassembly Golgi cisternae unstack, while coat protein I (COPI) vesicle budding in the absence of fusion consumes the cisternal rims, and a COPI independent pathway consumes the cisternal cores. Release of p115, a vesicle tethering protein, from the Golgi membrane at mitosis is shown to contribute to the unstacking process. Rab GTPases are shown to be required for correct disassembly. An assay is established to study the COPI independent pathway. The regeneration of Golgi cisternae at telophase proceeds via two intersecting pathways controlled by the N-ethylmaleimide sensitive factor (NSF) and p97 ATPases. Stacking of these reassembling cisternae requires Golgi ReAssembly Stacking Protein (GRASP) 65. During reassembly, p115 in conjunction with its two Golgi receptors, GM130 and giantin, is required to stack nascent cisternae, at a stage upstream of GRASP65. The activity of a G protein is also required coincident or downstream of p115. A novel GRASP, GRASP55, also plays a role in cisternal stacking. Phosphorylation of p115 by a casein kinase II like activity is essential for NSF catalyzed cisternal regrowth, but not cisternal stacking, and may strengthen the giantin- p115-GM130 complex. The first coiled-coil domain of p115 can interact with SNARE molecules and is required for NSF catalyzed cisternal regrowth. NSF catalyzed cisternal regrowth does not require the ATPase activity of NSF. Finally, a novel p97/Ufd1p/Npl4p complex is unable to catalyze cisternal regrowth.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Tubulovesicular clusters; Cisternal regrowth