Biology 2382B Lecture Notes - Microtubule, Tubulin
2 Mar 2012
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Document Summary
Intricate network of protein filaments that extend throughout the cytoplasm: microtubules 25nm, microfilaments 7-9 nm. Dimer is basic subunit 8nm. Form a structure called a protofilament all in a single row. Protofilaments come together the form hollow tube like structure, which is the microtubule, usually 13 protofilaments. Have polarity - on one end and on the other end. Structure has a seem which suggests that a flat structure folds up into a tube. 25nm diameter, up to 100s of m long. Binds permanently to gtp, can hydrolyze gtp so can be bound to gtp or gtp. As the polymer (protofilament) grows, "s gtp is hydrolyzed. Singlets most common 13 protofilaments forming a single tube of 25nm diameter; can grow and shink. Doublets (cilia and flagella) and triplets (basal bodies, centrioles) which are stable can also be formed made of 13 protofilament tube with one or two 10 protofilament tubes attached. Microtubules organized in the interior of the cell.
