GENE 540 Midterm: Motor Proteins & Centrosomes
Document Summary
Motor proteins transport cargo (vesicles, organelles, and even other microtubules) This is just a picture showing us that proteins and even whole organelles can be moved via these motor proteins: Kinesins go in the positive direction (toward the periphery) Dynesins go in the negative direction (toward the centrosome) The gtp-b-tubulin that gets bound to the microtubule (this is polymerization) For depolymerization, the gtp gets hydrolyzed to gdp. There are also proteins that help stabilize and destabilize the microtubules. For example, if the gtp-cap is hydrolyzed prematurely and there is no more new gtp, then this would destabilize the structure. A microtubule with gtp- -tubulin on the end of each protofilament is strongly favored to grow. However, a microtubule with gdp- -tubulin at the ends of the protofilaments forms a curved structure and will undergo rapid disassembly. Switches between growing and shrinking phases, called rescues and catastrophes, can occur, and the rate of switching is regulated by associated proteins.
