The table below summarizes the frequencies with which restriction endonuclease sites occur in commonly used DNA molecules. Detailed restriction maps can be found on DNA sequences and maps. The sites listed in these tables were identified by computer analysis of published sequences. Although we have tried to ensure their accuracy, the sites have not necessarily been confirmed by experimentation. When the same specificity is displayed by several enzymes, the site is listed by the name of the enzyme that is available from New England Biolabs. Other enzymes with the same specificity are listed in the table of isoschizomers. Recognition sequences are written 5´ to 3´.