INDUCTION OF MUTATION OF A SYNTHETIC C-HA-RAS GENE CONTAINING HYPOXANTHINE

The second base of codon 61 of a synthetic c-Ha-ras gene was replaced with a hypoxanthine residue in a site-specific manner. Transfection of this gene into NIH3T3 cells by the calcium phosphate procedure result ed in increased focus formation. Total DNA was extracted from transfor med cells, and the sequences of the inserted c-Ha-ras DNA were analyze d by the polymerase chain reaction-single-strand conformation polymorp hism method. Mutations with A (or hypoxanthine) to G transition were d etected exclusively. These results suggest that the synthetic c-Ha-ras gene can be used for investigations of mutageneses caused by DNA lesi ons.