Institute of Human Genetics; Howard Hughes Medical Institute (HHMI)
Capecchi, Mario R.;
Sharp, J. D.; Capecchi, Nancy E;
Altered enzymes in drug-resistant variants of mammalian tissue culture cells.
Two selective procedures are compared in an effort to isolate variants of mouse L cells containing structural gene mutations. Among the resulting variant cloned cell lines are found two types of alterations in theenzyme hypoxanthine phosphoribosyl transferase (EC 22.214.171.124.) (1): enzyme with altered kinetic constants causing in vivo and in vitro resistance to 8-azaguanine; and (enzyme with altered heat sensitivity in vitro. These results support the view that tissue culture cell variantscan arise from structural gene mutations.
National Academy of Sciences of the United States of America.
Drug Resistance; Azaguanine; Clone Cells; Hypoxanthines;