They were first discovered by Werner Arber during attempts to render E. coli B/r sensitive to the lambda phage.  Most of them fall into the type II variety, and examples such as HpaI and HaeIII result in blunt end digests.  More useful ones include NotI and BamHI, which create 5-prime phosphate extensions and leave characteristic "sticky ends" in order for DNA ligases to add different inserts.  Perhaps the most common example of these proteins is
They were first discovered by Werner Arber during attempts to render E. coli B/r sensitive to the lambda phage.  Most of them fall into the type II variety, and examples such as HpaI and HaeIII result in blunt end digests.  More useful ones include NotI and BamHI, which create 5-prime phosphate extensions and leave characteristic "sticky ends" in order for DNA ligases to add different inserts.  Perhaps the most common example of these proteins is one that cleaves the site GAATTC, known as EcoRI.  FTP, identify these digestion proteins used to cleave DNA at specific sites.
They were first discovered by Werner Arber during attempts to render E. coli B/r sensitive to the lambda phage.  
restriction endonuclease(s) or restriction enzymes