Localization of an exchangeable GTP binding site at the plus end of microtubules

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Science  20 Aug 1993:
Vol. 261, Issue 5124, pp. 1044-1047
DOI: 10.1126/science.8102497


Microtubule polarity arises from the head-to-tail orientation of alpha-beta tubulin heterodimers in the microtubule lattice. The identity of the polypeptide at each end of the microtubule is unknown, but structural models predict that the beta-tubulin end contains an exchangeable guanosine triphosphate (GTP) binding site. When GTP-coated fluorescent beads were incubated with microtubules, they bound specifically to plus ends, suggesting that tubulin is oriented in microtubules with beta-tubulin toward the plus end.

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