Temperature-sensitive hypoxanthine-guanine phosphoribosyltransferase in mutant Chinese hamster cells

By selecting variants of Chinese hamster cells that were resistant to 6TG at 39 degrees C, but which would continue to grow in HAT medium at 33 degrees C, we have isolated cell lines with thermosensitive phenotypes for HGPRT controlled properties. THE HGPRT produced by those clones is temperature sensitive. These results indicate that the selected clones carry missense mutations in the structural gene for the enzyme.