What is restriction enzyme type 1?

Type 1 restriction enzymes recognize certain DNA sequences and make cuts at random sites as far as 1000 base pairs away from the recognition site. The random cleaving is followed by DNA translocation because this enzyme is also a molecular motor. This enzyme type is composed of three polypeptides: restriction (R), methylation (M) and DNA sequence-recognition (S) subunits. Type 1 restriction enzymes are bifunctional enzymes with both restriction and methylase activities. They hold little practical value since they do not create distinct restriction fragments or gel-banding patterns.