title: Localization of an exchangeable GTP binding site at the plus end of microtubules.
abstract: 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.
authors.affiliation: Department of Pharmacology, University of California, San Francisco 94143-0450.
authors.forename: T J
authors.initials: TJ
authors.lastname: Mitchison
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D005033:Ethylmaleimide; D006160:Guanosine Triphosphate / Q000378:metabolism*; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism*; D017239:Paclitaxel; D013768:Tetrahymena; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D014404:Tubulin; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D005033:Ethylmaleimide; D017239:Paclitaxel