BIS104 Slide11

BIS104 Slide11 - Lecture 11 1. Molecular motors 2. Cell...

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Unformatted text preview: Lecture 11 1. Molecular motors 2. Cell adhesion Filament Associated Proteins.. a. AF plus end capping proteins: CapZ b. MT plus end binding proteins: MAP, catastrophin , EB1 2. Cross-linking and bundling proteins (AF) 1. Plus end binding proteins 3. Severing (cleaving) proteins (AF) - Gelsolin (AF) Spectrin , -actinin, Fimbrin, Villin and Filamin Free subunit associated proteins..(FYI) 1. Proteins that bind to AF subunits: Profilin, Thymosin 2. Proteins that bind to MT subunits: Stathmin Nucleation 1. Proteins that help to nucleate AF : ARP, WASp 2. Proteins that help to nucleate MT : -tubulin Cytoskeletons are the source of all cell movement They are mediate the movements of organelles and particles within a cell Myosins ( AF ) Kinesins and Dyneins ( MT ) Molecular motors act on cytoskeletons to move things around Figure 16-54a Molecular Biology of the Cell ( Garland Science 2008) Myosin II Actin-based motor proteins: the Myosin superfamily -each myosin molecule: 2 heavy chains and 4 (2x2) light chains form bipolar myosin thick filaments Motor activity of the myosin head Figure 16-61 (part 1 of 2) Molecular Biology of the Cell ( Garland Science 2008) How does myosin walk along an actin filament? Binding of ATP detach myosin head from AF ATP hydrolysis causes the myosin lever arm to bend Figure 16-61 (part 2 of 2) Molecular Biology of the Cell ( Garland Science 2008) ATP hydrolysis causes the myosin lever arm to bend Release of ADP causes power stroke Release of Pi causes binding of myosin head to AF Skeletal muscle cells Myoblasts (muscel cell precursor) fuse to form multi-nucleated muscle cells Myofibril is a cylindrical structure (in the cytoplasm), -is as long as the muscle cell, consists of repeated Sarcomeres Figure 16-73a Molecular Biology of the Cell ( Garland Science 2008) a few cm long Figure 16-74 Molecular Biology of the Cell ( Garland Science 2008) Skeletal muscle myofibrils and sarcomeres Sarcomeres = contractile units ~ 2 m long Organization of accessory proteins in a sarcomere Figure 16-76 Molecular Biology of the Cell ( Garland Science 2008) Figure 16-55a,b Molecular Biology of the Cell ( Garland Science 2008) Myosin II form bipolar myosin thick filaments Each myosin head binds to ATP and user ATP hydrolysis to move towards the plus end of AF Actin filament Figure 16-55a,b Molecular Biology of the Cell...
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BIS104 Slide11 - Lecture 11 1. Molecular motors 2. Cell...

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