ISOLATION AND IDENTIFICATION OF MICROTUBULE PROTEIN AND ITS APPLICATION IN ANTICANCER DRUG SCREENING

Partially purified microtubule protein was prepared from porcine brain by two cycle polymerization-depolymerizations in MES buffer. Two main bands, α-tubulin (M. W. 58,000)and β-tubulin (M. W. 54,000) were obtained on SDS polyacrylamide gel electrophoresis. ATP and GTP, at a concentration of 1 mM was found to have comparable activity in supporting microtubule polymerization. The effect of vincristine on the microtubule protein was examined. Low concentration of vincristine (0.75 μM)inhibited the microtubule polymerization, but high concentration (24 μM)induced aggregation which could not depolymerize at low temperature (0—4℃). Harringtonine, homoharringtonine and isoharringtonine did not show significant activity on this model.