A mutational hotspot in the aprt gene of Chinese hamster cells

Abstract Early work with adenine phosphoribosyltransferase-deficient mutants of CHO cells suggested that a site existed in the third exon of this gene which was preferentially susceptible to mutation by ethyl methanesulphonate. To determine whether this was real we analysed a large collection of induced mutants, and generated a high-density mutational spectrum for this exon. In addition, 4 sites outside exon 3 were analysed by blot. 37 mutations were found in 19 available sites, six of which were at nucleotide 1365, 1 of 2 sites in the putative hotspot ( P