## Description

This track shows restriction enzyme recognition sites. At different browser zoom levels (categorized in the table below by the number of bases visible), different sets of enzymes are shown. "Base-level" refers to the browser zoom level at which individual bases are displayed in the Base Position track. Displays of custom enzyme sets override the table: in these cases, the restriction sites are consistent across all zoom levels. "Primary" enzymes are the canonical isoschizomer for each cutsite, usually the first isolated or most readily available.

The base-level display shows the detail of the cutting pattern of the enzyme as well as the presence of any ambiguous or redundant nucleotides in the cutsite. The four standard bases, G, A, T and C, are displayed in black, whereas non-unique bases using IUPAC designations (R, Y, N, etc) are displayed in blue.

The term "isoligamer" in the enzyme details section was coined to designate enzymes that produce single-stranded overhanging "sticky" ends that are ligatable to each other.

Zoom level (in bases) | Enzyme set displayed
--- | ---
Base-level | All "primary" enzymes from REBASE
Base-level - 2,999 | Restriction sites for "primary" enzymes five bases and larger.
3,000 - 19,999 | Restriction sites for "primary" enzymes six bases and larger
20,000 - 249,999 | The following set of commonly-used enzymes: ClaI, BamHI, BglII, EcoRI, EcoRV, HindIII, PstI, SalI, SmaI, XbaI, KpnI, SacI, SphI
> 250,000 | None displayed

## Credits

Thanks to REBASE for providing these data.