Isolation of the chicken thymidine kinase gene by plasmid rescue.

We have used the bacterial plasmid pBR322 as a vehicle to isolate genes coding for selectable markers from higher eukaryotes. In this way, we have obtained the chicken thymidine kinase (tk) gene as a 2.2-kilobase EcoRI/HindIII insert in BR322. The cloned gene transforms tk- animal cells with an efficiency equal to that of the cloned herpes simplex virus-1 tk gene.