TY - JOUR
T1 - Taxoi binds to cellular microtubules
AU - Manfredi, James J.
AU - Parness, Jerome
AU - Horwitz, Susan Band
PY - 1982/9/1
Y1 - 1982/9/1
N2 - Taxol is a low molecular weight plant derivative which enhances microtubule assembly in vitro and has the unique ability to promote the formation of discrete microtubule bundles in cells. Tritium-labeled taxol binds directly to microtubules in vitro with a stoichiometry approaching one (Parness, J., and S. 8. Horwitz, 1981, J. Cell Biol. 91:479-487). We now report studies in cells on the binding of [aH]taxol and the formation of microtubule bundles. [aH]Taxol binds to the macrophagelike cell line, J774.2, in a specific and saturable manner. Scatchard analysis of the specific binding data demonstrates a single set of high affinity binding sites. Maximal binding occurs at drug concentrations which produce maximal growth inhibition. Conditions which depolymerize microtubles in intact and extracted cells as determined by tubulin immunofluorescence inhibit the binding of [aH]taxol. This strongly suggests that taxol binds specifically to cellular microtubules. Extraction with 0.1% Nonidet P-40 or depletion of cellular ATP by treatment with 10 mM NaNa prevents the characteristic taxol-induced bundle formation. The binding of [aH]taxol, however, is retained under these conditions. Thus, there must be specific cellular mechanisms which are required for bundle formation, in addition to the direct binding of taxol to cytoplasmic microtubules.
AB - Taxol is a low molecular weight plant derivative which enhances microtubule assembly in vitro and has the unique ability to promote the formation of discrete microtubule bundles in cells. Tritium-labeled taxol binds directly to microtubules in vitro with a stoichiometry approaching one (Parness, J., and S. 8. Horwitz, 1981, J. Cell Biol. 91:479-487). We now report studies in cells on the binding of [aH]taxol and the formation of microtubule bundles. [aH]Taxol binds to the macrophagelike cell line, J774.2, in a specific and saturable manner. Scatchard analysis of the specific binding data demonstrates a single set of high affinity binding sites. Maximal binding occurs at drug concentrations which produce maximal growth inhibition. Conditions which depolymerize microtubles in intact and extracted cells as determined by tubulin immunofluorescence inhibit the binding of [aH]taxol. This strongly suggests that taxol binds specifically to cellular microtubules. Extraction with 0.1% Nonidet P-40 or depletion of cellular ATP by treatment with 10 mM NaNa prevents the characteristic taxol-induced bundle formation. The binding of [aH]taxol, however, is retained under these conditions. Thus, there must be specific cellular mechanisms which are required for bundle formation, in addition to the direct binding of taxol to cytoplasmic microtubules.
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U2 - 10.1083/jcb.94.3.688
DO - 10.1083/jcb.94.3.688
M3 - Article
C2 - 6127342
AN - SCOPUS:0020419247
SN - 0021-9525
VL - 94
SP - 688
EP - 696
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 3
ER -