Open AccessHYBRIDIZATION OF HAMSTER CELLS WITH HIGH AND LOW FOLATE REDUCTASE ACTIVITY
Author(s) -
John W. Littlefield
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.62.1.88
Subject(s) - aminopterin , overproduction , baby hamster kidney cell , hamster , biology , reductase , repressor , enzyme , biochemistry , microbiology and biotechnology , cell culture , genetics , cell , gene , gene expression , immunology , methotrexate
These studies concern the question whether diffusible repressors control the syntheses of enzymes in mammalian cells. First, clonal sublines of baby hamster kidney (BHK 21/13) cells in culture were selected in stepwise fashion for resistance to aminopterin. These sublines survived in concentrations of aminopterin that were up to 104 times higher than those tolerated by wild-type cells because they contained up to 125 times as much folate reductase, probably due to overproduction of the enzyme. When five resistant sublines were hybridized to wild-type lines, 32 of 35 hybrid clones contained intermediate levels of reductase activity. This suggests that overproduction of reductase is not due to loss of a diffusible repressor.