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11 Cards in this Set
- Front
- Back
Characteristics of muscular microfilaments
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- stable, hexagonal crystalline array of actin=thin and myosin=thick
-highly ordered sarcomeric units -Electric signal causes Ca2+ to release and contract myofibril? |
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Characteristics of non-muscular microfilaments
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-Highly dynamic, less-ordered arrays
1- 10% of all proteins, also single cell orgs - Used in epithilia, endothelial, fibroblasts, nerve, blood cells - functions- cell shape, structure, polarity, vesicle movement, trafficking |
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Actin
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- Microfilaments are made of helical actin arrays
- Structually and functionally well conserved- actin binding sites to copolymerize, myosin sites , tropomyosin binding sites |
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Actin polymerization process
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monomers- nucleation- elongation- steady-state equilibrium
G-actin is globular F-actin is filamentous |
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Factors of actin filament assembly
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salt K+/Mg2+
ATP Actin |
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Protein that adds on actin monomers to a filament
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formin dimer
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Template for actin synthesis
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ARP complex, 2-3 which are activated by some other facter
Lines up on actin at 70 degree angle |
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Functions and specializations of non-muscle microfilaments
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-Cell cortex- structural rigidity and stabilize plasma membrane
- stress fibers- create tension in fibroblasts and endothelial cells - Cell surface extension- filibodia, etc. increase surface area of cell and can probe environment, some mobile activity - Stereocilia- detect sound waves in ear. Some mesh-like activity is crucial |
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Different types of actin tension structures
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contractile bundle in cell skeleton
gel-like network in cortex tight parallel bundle in filipodium |
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Components of focal adhesion
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specific way to bind to ECM
fibronectin, paxillin, talin, vinculin f-actin and alpha- actin capping protein plasma membrain |
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RHO family of GTPases that regulate actin filament
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Cdc42- filipodia
Rac1- lamellipodia - activates RHG Rho- stress fibers 1st column act in a cascade |