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17 Cards in this Set
- Front
- Back
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What are the 2 types of Nucleating proteins.
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1. ARP2/3 Complex
2. WASp |
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Describe ARP2/3 Complex
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7 subunits:
ARP: acting related proteins critical in the "leading" edge of cells that move New MF formation in "branch" formation |
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Describe WASp.
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Binds to ARP2/3 complex
promotes assembly of MF Often works with G-protein coupled receptors and RTKs |
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Describe WASp subfamily
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podosome formation
-macrophages, dendritic cells, pseudopodia |
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Scar/wave subfamily
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lamellipodia, pseudopodia
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Describe receptor tyrosine kinases fig 15.15
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Always function as a dimer when activated
Phosphorylated tyrosine serves as binding site for additional proteins RAS, RAC, Rho: all G-proteins Can P a number of proteins |
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Describe Rho (RTK)
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Critical G-protein in many MF mediated processes
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Describe the function of RAS (RTK)
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Cell proliferation
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Describe Geb2 (RTK)
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Protein with SH2 domain
links activated receptor to other proteins |
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Describe filament severing proteins.
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Gelsolin, brevin
Severs MF into shorter fragments cytoplasm becomes more "liquid"- changes velocity of cytosol Some bind to free ends, inhibiting polymerization Gelsolin: Ca release Via IP3 binding to smooth ER or Ca influx across PM as Ca levels decrease, PIP2 binds gelsolin. |
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Describe ectoplasm.
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More viscous portionof cytoplasm
MF arrays Myosin I: stabilizing the MF that are already there X-links MF and stabilizes them Gel-phase |
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Describe endoplasm.
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Less viscous
center of cell MF very short: not linked together, Myosin II pushes the less viscous phase into the pseudopod: contraction and pushing Endoplasm is pushed towards "front" of cell, becomes the hyaloplasm (clear) Filamin and alpha-actinin promote MF arrays in pseudopodia Profilin promotes actinin polymerization Gelsolin and cofilin imortant for severing acting filaments in endoplasm. Chemotaxis in amoeba utilize 7 membrane spanning receptors Block Na/Arc activity inhibits movement in some amoeba. |
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Describe X-linking proteins
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Form bundles or arrays (networks)
Called 1. Network forming proteins or 2. Bundling proteins Have at least 2 MF binding sites |
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Bundling proteins (X-linking). Name 4
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Fascin
Fimbrin Villin Alpha actinin |
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Network forming proteins (X-linking). Name 3
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Filamin
ADP Gelatin *more flexible, produce arrays |
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What are the types of MF bundles made by bundling proteins?
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1. Parallel bundles
MF oriented in same direction Microvilli, stereocilia, very stable and long lived 2. Contractile bundles MF arranged in opp. orientation to each other. Usually associated with Myosin II. Focal adhesions: help achore cell to bottom of culture dish. Isometric force, not contractile |
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Describe membrane binding proteins
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1. Promote outward pushing of PM
2. Stabilize shape of PM "spot weld" PM to actin filaments Dystrophin: muscles |
