Endogenous gene systems for the study of mutational specificity in mammalian cells

Determination of the DNA sequence alterations produced by various mutagens is a prerequisite for understanding mechanisms of mutagenesis. With recent technical advances that permit rapid isolation of mutant alleles, the mammalian genome has become accessible to this type of analysis. Here we discuss the growing data base on mutational specificity in mammalian cells, with an emphasis on the information obtained from studies of two endogeneous genetic loci, aprt and hprt.