ID #1949

In lecture you talked about how hydrolyzing the GTP molecule in the beta-tubulin was the signal for the beta-tubulin to favor depolymerize, and that the GTP in the alpha-tubulin doesn't get hydrolyzed. How does the alpha-tubulin know when to depolymerize then?

It's important to remember that tubulin gets added as dimers of alpha and beta tubulin, so it's the dimers that fall off during depolymerization. It is true that the alpha subunit does not have its GTP hydrolyzed, but that's not a significant influence on the attraction or repulsion that the dimer demonstrates for its neighbors. So when tubulin falls off a microtubule, the alpha subunit is leaving along with the beta subunit; they do not arrive or leave separately.

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