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

Science. 1993 Aug 20;261(5124):1044-7. 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Binding Sites
  • Binding, Competitive
  • Ethylmaleimide
  • Guanosine Triphosphate / metabolism*
  • Microtubules / chemistry
  • Microtubules / metabolism*
  • Paclitaxel
  • Tetrahymena
  • Tubulin / chemistry
  • Tubulin / metabolism*


  • Tubulin
  • Guanosine Triphosphate
  • Adenosine Triphosphate
  • Ethylmaleimide
  • Paclitaxel