Lecture 7--cell motility

Fish keratocytes have large actin filled lamellipodia

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Unformatted text preview: at Wadsworth lab The Arp2/3 complex nucleates actin filaments and promotes branching downstream of signaling pathways ARP: acting related protein; not actually in actin faily but simolar structure to actin find activated forms in lamelopodia, places moving ARP: Actin Related Protein. Has similar structure to actin. one of the eays that extracellular cues can • Seven conserved subunits including Arp2 and Arp3. • Is activated at the surface of Listeria by the ActA protein to stimulate actin polymerization and bacterial propulsion. • Localizes at motile regions of cell. • Generates new actin filaments in a stimulusresponsive and spatially controlled fashion. The Arp2/3 complex nucleates actin filaments and promotes branching downstream of signaling pathways ARP: Actin Related Protein. Parts of the ARP complex structurally mimic actin. to a monomer acting, the interface loooks like the end of the promotes the formatino of new filament there ARP2 green (ARP2; nucleateds filaments at 70 degree angle; Figure 16-34c Molecular Biology of the Cell (© Garland Science 2008) Electron microscopy provides a static, but high resolution view of ARP2/3 in actin organization in grwoth of the cytoskeleton cones Wildtype growth cone Arp2/3 deficient growth cone Arp2/3 complex is important for filopodia formation, growth cone motility, and neuritogenesis in neuronal cells. Korobova F, Svitkina T. Mol Biol Cell. 2008 Apr;19(4):1561-74 Actin Dynamics 31 How does the actin cytoskeleton respond to outside cues to polymerize specifically at the leading edge? Activators of actin nucleators can respond to extracellular signals Figure 16-34b Molecular Biology of the Cell (© Garland Science 2008) WASp family proteins respond to extracellular signals to activate Arp2/3 mutation in wasp causes a n immune disease; protein involved in cell migration have receptor that activates down stream proteins, recruits and activated WASp, activate Arp2/3 and activate actin polymerization at the leading edge Thrasher AJ (2002). WASp in immune-system organization and function. Nat Rev Immun...
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