Pactamycin resistance in CHO cells: Morphological changes induced by the drug in the wild‐type and mutant cells

Stable mutants resistant to pactamycin (PacR), a polypeptide chain initiation inhibitor, have been selected in a single step in Chinese hamster ovary (CHO) cells. The sensitivity of protein synthesis in mutant cell extracts to pactamycin indicates that resistance involves an alteration in the permeability of this drug. The failure of PacR mutants to show cross-resistance to other compounds provides further indication that the lesion is …