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Investigations into membrane protrusions mediated by IRSp53 IMD

Waller, Andrew Philip (2010)
Ph.D. thesis, University of Birmingham.

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Cells depend on the actin cytoskeleton and the structures it forms for a wide range of processes. IRSp53 acts downstream of cytoskeleton master regulators Rac and Cdc42 in the formation of lamellipodia and filopodia, respectively. IRSp53 interacts with many other effectors in the formation of these structures, via various protein interaction domains. IRSp53 also contains an IMD (IRSp53/MIM homology domain), which is able to induce formation of filopodia-like structures when overexpressed in cells. Early reports suggested that the IMD exerts its effect by bundling actin filaments. However, the structure of the IMD revealed that it is related to BAR domains, which can induce membrane curvature by binding to membranes. It is still unsure whether IMD activity is dependent on actin or membrane interactions, or both. Data are presented here showing that actin destabilizing drug cytochalasin D prevents extension of IMD protrusions, suggesting a role for actin in this process. Fluorescence recovery after photobleaching experiments suggest that a large proportion of IMD is stably associated with the protrusions. Finally, in vitro lipid binding experiments suggest that IMD binds to membranes by mainly electrostatic interactions. These findings suggest that IMD activity may depend on interactions with both actin filaments and membranes.

Type of Work:Ph.D. thesis.
Supervisor(s):Fütterer, Klaus and Machesky, Laura
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Biosciences
Subjects:QH301 Biology
Institution:University of Birmingham
ID Code:860
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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