Genetic and biochemical studies with the adenosine analogs toyocamycin and tubercidin: Mutation at the adenosine kinase locus in Chinese hamster cells

The pyrrolopyrimidine nucleosides toyocamycin and tubercidin show several unique features of growth inhibition in Chinese hamster ovary (CHO) cells. Stable mutants which are more than 500-fold resistant to these drugs are obtained in CHO cells at a strikingly high frequency of approximately 10−3,in the absence of mutagenesis. The mutants resistant to toyocamycin (Toyr)and tubercidin (Tubr)exhibit similar crossresistance patterns to the two …