Catastrophe

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mcdull1016
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Catastrophe

Post by mcdull1016 » Tue Aug 02, 2005 11:55 pm

What is catastrophe? I only know this is related to the microtubules growth and shrinkage.

sdekivit
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Post by sdekivit » Wed Aug 03, 2005 9:05 am

catastrophe is the phenomenon that growing microtubles suddenly loose their GTP-cap and rapidly depolymerize. This is due to thermodynamic instability.

When the tubulin concentration in the cell gets to the critical value, then the GTPcap (needed for polymerization of the microtubule) is hydrolized, weaking the bond between the tubulinmolecules and curves the strands (shrinkage of microtubles is due to curling of mprotofilaments). Therefore the microtubule is rapidly hydolized. During this hydrolysis when the concentration of tubulin in the cell has increased, growth will start again (during shrinkage GTPcontaining tubulin can still add. When there are enough GTP-tubulin molecules bound, the GTP-cap is regained and growth can occur again), known as 'rescue'.

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