BIO 3153 Lecture Notes - Lecture 5: Spindle Apparatus, Pericentriolar Material, Tau Protein
15 Dec 2017
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Document Summary
Lecture 5 cytoskeleton ii: centrioles and centrosome. Centrosome contains 2 centrioles near nucleus, sit at right angles, task is to organize the pericentriolar material (contains gamma-tubulin), dynamic instability causes merging of microtubules and formation of mitotic spindle. Centrioles are 9 triplets of microtubules, (-) ends anchored, (+) ends emanating from astral configuration, lumen contains y-tubulin: actin filaments. Af proteins density highest in cortex, facilitated by abp and arp: arp2-3 complex bind at minus end, promote branching, 70degrees, contains 7 proteins. Af initiated by formin (abp), corrects alignment for polymerization. Subunit pools: actin and tubulin in high concentration in cytosol, accessory proteins may sequester unused subunits and sequestered proteins are not hydrolyzed, provide control of elongation. Thmosin sequesters actin by making polymerization less favorable, profilin recruits monomers and competes with thymosin to promote assembly. Stathmin sequesters tubulin to prevent polymerization, decreases effective tubulin and promotes catastrophe. Maps tau protein unable to space the mts properly induces neurodegeneration (alzheimer"s disease)
