Abstract
The hybrid plasmid pTK1 consists of the herpes simplex virus type 1 (HSV-1) BamHI p fragment, which contains the thymidine kinase (TK) gene, inserted into the vector pAT 153. When pTK1 DNA was microinjected into nuclei of Xenopus laevis oocytes, functional HSV-1-specific TK was produced, showing that transcription and translation of the gene occurred. Investigation of pTK1-specific RNA by Southern blot hybridization revealed that all regions of the hybrid plasmid were transcribed by RNA polymerase II, but sequences present in TK mRNA were most highly represented in stable transcripts.