Lecture 7--cell motility

Lamalice l le boeuf f huot j circ res 2007 mar

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Unformatted text preview: irc Res. 2007 Mar 30;100(6):782-94. Two ways for actin filaments to promote cell movement 1. Myosin-driven movement of actin filaments push forward the membrane or promote contraction. 2. Actin monomers are inserted between the tip of actin filaments and the edge of the cell. Actin polymerization at the leading edge pushes the membrane forward light blue: ADP bound actin monomers dak blue: ATP bound actin monomers ATP bound in the front, ADP bound in the back; as ATP-actin binds, coffilin takes them away from + end; grows on - end and breaks down on + end treadmilling treadmilling has to be polarized; signals from outide tht can engage with these proteins to start 31 treadmilling process Actin polymerization at the leading edge pushes the membrane forward 31 Actin polymerization at the leading edge pushes the membrane forward FRAP of GFP-actin, from Zaoui et al. spekeled microscopy: Actin polymerization at the leading edge pushes the membrane forward FRAP of GFP-actin, from Zaoui et al. Actin polymerization at the leading edge pushes the membrane forward FRAP of GFP-actin, from Zaoui et al. if not in filamwnt, what are they? what is actin doing when not in filament? G actin, glubular actin, monomoers of actin never reaches 100 because it is always being removed so always getting less stable higher affinitiy for filament and oligomer than monomers; end growing (+ end) barbed, end shrinking (-) end (pointing end0 chart shows on x axis time: when you add ATP; y axis: % of subunits in filaments F actin if wanted to speed up process, you can seed it with a preformed filament; there would not be a slow step Figure 16-10a Molecular Biology of the Cell (© Garland Science 2008) 16 Figure 16-10b Molecular Biology of the Cell (© Garland Science 2008) Actin treadmilling whats different between the in vivo and vitro environment: ther ea re a bunch of enzymes whos jobs are to speed it up Filament turnover In vitro: 3 "m / 90 min In vivo (lammellipodium): 3 "m / 1 min Actin binding proteins regulate actin dynamics to control motility 1. ADF/Cofilin and profilin promote actin tre...
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