Figure 1.

Covalent and tubulin-specific binding of T138067. (A) Structure of T138067. (B) Binding of ³H-T138067 to cellular β-tubulin. Lane 1, Coomassie-stained proteins derived from MCF7 whole-cell extracts after SDS/PAGE. MCF7 cells were treated with 400 nM ³H-T138067 for 3 hr; lane 2, autoradiogram of membrane with immobilized protein from the gel shown in lane 1; lane 3, immunoblotting of the membrane shown in lane 2 with anti-β-tubulin antibodies; lane 4, autoradiogram of immunopurified cellular ³H-T138067-labeled β-tubulin derived from MCF7 whole-cell extracts (lane 1). Immunopurification was performed with antibodies to β₂-tubulin. Molecular size markers are shown on the left.