Effects of ionizing radiation on the polymerization of microtubules in vitro.

Exposure of phosphocellulose-purified 6S tubulin to ionizing radiation results in a reduction or loss in its ability to participate in polymerization. Evidence is presented which correlates this loss in ability to polymerize with a reduction in the number of titratable sulfhydryl groups and a lowered affinity for guanosine triphosphate.