MCD BIO 165A Lecture Notes - Lecture 8: Petri Dish, Stress Fiber, Actinin
22 Nov 2018
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Lecture 8 extracellular motility: polarized cell in direction of migration, anchored in collagen fibrils in ecm, disproportionate amount of actin in leading edge vs stress fibers (actin + myosin) in. E. g. leukocyte fighting bacteria dependent on actin cytoskeleton actin filament assembly & disassembly: g-actin"s shape provides orientation/polarity of filament. Monomers added more often to +/barbed end. Monomers lost often from -/pointed end: mostly studied in vitro. Petri dish + g-actin -> nothing happens, unless have atp. For actin filament to grow, need to add atp; stop adding atp (atp has half life) -> depolymerization: atp-bound actin -> nucleation -> filament polymerization, stability dependent on atp. Affinity g-actin have for each other depends on conformation having to do with atp: when atp hydrolyzed to adp -> affinity lost -> g-actin falls off, steady state of filament size. Important for: allows decision making: where to go/polymerize, depending on signaling pathway: study of actin filament: monocytogenes uses actin in host cell for locomotion.
