Phenotypic conversion of TK-deficient cells following electroporation of functional TK enzyme

The ability to phenotypically rescue a mutant (Rat-3, thymidine kinase-deficient) cell line by electroporation of functional TK enzyme has been investigated. Extracts of electroporated cells showed a 35-fold increase in TK enzyme levels under conditions where greater than 90% of the cells remained viable. The electroporated enzyme was intracellular, as demonstrated by the fact that cells were able to utilize exogenous [3H]thymidine for DNA synthesis. By in situ autoradiography, 82% of electroporated cells contained functional enzyme and incorporated [3H]thymidine into DNA. Thus, this technique can efficiently provide a missing metabolic function to cultured mammalian cells.