Isolation of transforming DNA: cloning the hamster aprt gene

Abstract

We have isolated the hamster gene coding for the enzyme adenine phosphoribosyl transferase (aprt) using gene transfer and molecular cloning of transforming DNA. Mouse aprt- cells were transformed to the aprt+ phenotype with the product of ligation of Hind III-cleaved hamster genomic DNA and pBR322 DNA. In this manner, the aprt gene was linked to a marked plasmid sequence and segregated from other hamster sequences. A lambda-recombinant phage containing pBR322 DNA sequences was isolated from a library of aprt+ transformed cell DNA. The phage DNA transfers hamster aprt+ activity at a frequency expected of a pure gene. Furthermore, sequences homologous to this clone are present in all hamster aprt+ transformants examined. This experimental design should in theory permit the isolation of any gene coding for selectable or identifiable functions for which DNA-mediated gene transfer can be effected.