10.20.09 Lecture - Cytoskeleton

10.20.09 Lecture - Cytoskeleton - 10/20/09 Cytoskeleton +...

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10/20/09 Cytoskeleton + Filaments etc. Actin – myosin – the motor that always go to plus end cuz of polarity. Intermediate fibers are more rigid – they’re like ropes, but doesn’t have the polarity Microtubules form the major high ways in the cell and play mechanical roles in most cell types. Microtubules structure from dimer to protofilament to microtubule. Creation of a tube has significance for energetics and strength. Staggaring the tubulin dimmers in the microtubule lattice gives the polymer a higher degree of shear strength – like making a rope of overlapping strands. Being a tube also has certain mechanical advantages-bicycles? Be aware that not all microtubules form 13 protofilament tubes. Tubulin is a GTPase. It gains a GTP when free and converts it to GDP in the microtubule. The GTP state alters the protofilament stability. Beta-tubulin forms a crown at the plus end of the microtubule. Alpha-tubulin binds to that beta and accelerates the hydrolysis of the GTP to GDP. The GTP tubulin dimmer has a higher binding affinity for the lattice than GDP tubulin.
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10.20.09 Lecture - Cytoskeleton - 10/20/09 Cytoskeleton +...

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