Differential effects of base-pair mismatch on intrachromosomal versus extrachromosomal recombination in mouse cells.

A. S. Waldman, R. M. Liskay

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To initially determine the effect that base-pair mismatch has on homologous recombination in mammalian cells, we have studied genetic recombination between thymidine kinase (tk) gene sequences from herpes simplex virus 1 and 2. These tk genes are approximately 81% homologous at the nucleotide level. We observed that, in mouse LTK- cells, intrachromosomal recombination between type 1 and type 2 tk sequences is reduced by a factor of at least 1000 relative to the rate of intrachromosomal recombination between homologous type 1 tk sequences. In sharp contrast, the rate of intermolecular or intramolecular extrachromosomal recombination between the heterologous tk sequences introduced by calcium phosphate or microinjection was reduced only by a factor of 3 to 15 compared with extrachromosomal homologous tk crosses. Our results suggest differences between the mechanisms of extrachromosomal and intrachromosomal recombination in mammalian cells.

Original languageEnglish (US)
Pages (from-to)5340-5344
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number15
StatePublished - Aug 1987


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