Restriction site

Also called a restriction recognition site.

A short, specific sequence of nucleotides (typically 4 to 8 bases in length) that is reliably recognized by a specific restriction enzyme. Because restriction enzymes usually bind as homodimers, restriction sites are generally palindromic sequences spanning both strands of a double-stranded DNA molecule. Restriction endonucleases cleave the phosphate backbone between two nucleotides within the recognized sequence itself, but other types of enzymes cut at one end of the sequence or at a nearby sequence.