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13 Cards in this Set
- Front
- Back
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What is Actin made of and how is it put together?
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Actin
Globular, Monomer Made by a 2-stranded helix |
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How is polarity important in actin filaments?
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Plus end-growing
Minus end-shrinking |
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What are the roles of actin filaments?
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Microvilli
Contractile bundles in cytoplasm Form leading edge projections in crawling cells Form the contractile ring in cell division Muscle contraction |
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Monomer Binding Proteins
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proteins like thymosin bind to the G-actins and prevent them from adding on to a growing actin filament; effectively decrease the concentration of free actin polymers
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Nucleating Proteins
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proteins like the ARP 2/3 complex and profilin interact with minus ends. promote growth often for new actin filaments
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Severing proteins
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Cut actin filament in half. Exposes ADP-Actin on plus end as well as on minus end. Rapid depolymerization and turns gel into liquid state.
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Cross-linking proteins
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Cross link actin filaments to create web-like structure
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End-binding proteins
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Two versions; one on plus end and one on minus end
prevent assembly or dis-assembly respectively |
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Stabilizing protein
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help stabilize the filament and prevent depolymerization, often by competing with depolymerizing proteins like cofilin/ADF for binding sites on the filament.
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Motor Proteins
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myosin is the major actin motor in that walks along all types of actin filaments
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Bunding Proteins
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help arrange actin filaments in stable, parallel structures
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Roles of myosin
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cell contraction is involved in cell crawling-pulling the tail end of the cell forward
form the cleavage furrow during cytokenesis can help cargo along tracks help muscles contract always go to plus end of actin |
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What diseases can happen from actin mutations?
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Muscular-Muscular dystrophy. No cytoplasmic chain to muscle plasma membrane
Neurological- synpatic function (Alzheimers, parkinsons, huningtons) Immunological cells Cancer- Metastasizing cells |
