Nucleosomal packaging of the thymidine kinase gene of herpes simplex virus transferred into mouse cells: an actively expressed single-copy gene.

We have studied the nucleoprotein structure of the herpes thymidine kinase gene introduced into mouse Ltk-aprt- cells by means of DNA-mediated gene transfer. Using the technique of Southern blotting, we examined staphylococcal digests of the nuclei from the relatively stable transformants that contain one or less integrated copies of the thymidine kinase gene per haploid genome. Out experiments show that, under selection for the active expression of this gene, it is packaged in nucleosomes with a repeat length identical to the average for the host mouse sequences.