alpha-Amanithin-resistant mutants of Chinese hamster ovary (CHO) cells.

Spontaneous and EMS-induced alpha-amanitin-resistant CHO cells have been isolated and characterized. DNA-dependent RNA polymerase II in cell-free extracts from a mutant (ARM-1) was partially resistant to alpha-amanitin. Growing mutants for several generations in the presence or absence of alpha-amanitin did not change the pattern of inhibition. The mutants grew with a lag following transfer to medium with or without alpha-amanitin. The mutants have an altered RNA polymerase II, and possibly an altered cell membrane.