A restriction site is the sequence of DNA nucleotides which are cut by a restriction enzyme . This is called the recognition sequence .
Most enzymes cut or cleave the DNA at the recognition sequence.
In this case, the recognition sequence and the cleavage site are identical. A few enzymes cut the DNA at a cleavage site some nucleotides away from the recognition sequence. The distinction is usually unimportant, except when the cut DNA is to be used in a recombinant DNA construction. The restriction sites for an enzyme on a specific large piece of DNA are often depicted as vertical lines on a restriction map .