Insertion element IS1 encodes two structural genes required for its transposition.

@article{Machida1984InsertionEI,
  title={Insertion element IS1 encodes two structural genes required for its transposition.},
  author={Yasunori Machida and Chiyoko Machida and Eiichi Ohtsubo},
  journal={Journal of molecular biology},
  year={1984},
  volume={177 2},
  pages={
          229-45
        }
}
The nucleotide sequence analysis of insertion element IS1 has shown that IS1 could have as many as six translational reading frames encoding possible proteins. In order to determine which reading frames are actual structural genes responsible for IS1-mediated recombination, we introduced base substitution mutations including nonsense mutations into all of the potential reading frames and examined the ability of these IS1 mutants to mediate cointegration between two plasmids. The results reveal… CONTINUE READING