Lecture 6--the cytoskeleton-1

Laminin extracelular membrane protein lamin found in

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Unformatted text preview: maintain nuclear shape kerainocytes: plate of cells that express too much keratin; (skin) keratin green; when two cells meet, spots in which lots of the keratin filaments are concentrated; probably representing desmosmes: they are attched to intermediate filaments Figure 16-20 Molecular Biology of the Cell (© Garland Science 2008) have polarity a dimer associates wih another dimer and makes tetramer, no longer polar have globular domain on both endsa and in bewtween, they have alpha helix; two of the monomers of intermediate filament will get together and coil around eachother, and form a coiled coil dimer Figure 16-19 Molecular Biology of the Cell (© Garland Science 2008) microtbules grow by adding subunits to one end, the (+) end; ppl took flurorescently conjugated filaments and e=injcted them into cells and saw that the filaments incorporated through the intermediate filaments; diffeent from actin and tubulin that is always only adding at one end; in order for the fluorescently cnojugted subunit os the intermediate filaments to Intermediate filaments may be anchored at junctions Distribution of keratin on an epithelial cell visualized with antikeratin antibodies Intermediate filaments can withstand deformation distinguishing featuee of these filaments is that they are very strong; if take filaments and apply deforming force (pull, push, crush) filaments will deform: see how each kind of filaments respond to it; the red ends mean that applied tooo much force that the filament breaks; microtubules disform the quickest, actin resist deforming forces but break pretty quickly. intermediate filaments: provide lots of strength and strucutral integrity Keratin deficiency can cause blistering dead cells onnective tissues kerating used to stablize desmosomes: causes cells to break right through te middle Actin filaments (microfilaments) • Present in highest densities at the periphery of cells • Made up of actin monomers (G-actin) assembled into filaments (F-actin) • Associated with the motor protein myosin • Interaction of actin and myosin enable cell contraction and migration • Actin polymerization is ATP-dependent Actin is in every cell and has diverse functions stereocylia; all actin filled, the tallest one is true celia and is made of microtubules adhesion hbelts; growth cones; impo...
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