MCB 2210 Lecture Notes - Lecture 12: Fluorescein, Tubulin, Microtubule
28 Oct 2016
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Document Summary
Key difference between actin and microtubules: beta can bind to and hydrolyze gtp to gdp. Both alpha a beta subunits can bind to gtp: minus end is slower growing end like actin, can also undergo treadmilling, very stable structure when bound to gtp. Growing fast = new subunits are in gtp bound state. Gtp cap describes tip of microtubule full of gtp bound dimers. Growth slows down= loss of gtp cap, all becomes gdp changes structure, causes curvature of protofilaments. How microtubules dynamics are studied: can take pure tubulin and watch polymerize in vitro. Unlike actin do not need to act salts, just have to have at 37 degrees celsius. If you cool it down it will depolymerize: has same critical concentration concept like actin. Polymer scatters more light monomer/dimer: attaching a florescent tag (rhodamine or fluorescin) To tubulin- easier to visualize when it is incorporated into microtubules. The role of nucleotides in microtubule dynamics: gtp hydrolysis accompanies microtubule assembly.
