CELL201 Lecture Notes - Lecture 13: Gelsolin, Polymerization, Filopodia
14 Mar 2018
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Drug effects: cytochalasins (fungal metabolites) prevent addition of new monomers to the mf by binding to the filament. Latrunculin a (toxin) bind to the monomer and prevents addition: phalloidin stabilises mfs and prevent depolymerization by binding to interface between subunits, cells that crawl have lamellipodia and filopodia. Cells that attach to surfaces have stress fibres. Filopodia are organised and polarised mf cables with their plus end at the tips. In lamellipodia the actin is less organised but generates force for movement of cells: g actin is bound to thymosin b4. Availability of g-actin is regulated by proteins like profilin: capz binds plus ends to prevent addition of subunits. Tropomodulin binds minus end to prevent loss of subunit. Arp2/3 branching is activated by wasp and wave/scar. Long actin filaments are needed for some cells (filopodia). Formin moves to the growing filaments to promote polymerisation: pip2 regulation:
