EcoRI is a restriction endonuclease enzyme, isolated from E. coli bacterium, which cuts through DNA at the palindromic sequence 5' GAATTC 3', and the opposite sequence on the other strand, 3' CTTAAG 5'. EcoRI 'cuts' through the sequence between the adenine base and the glycine base on each strand, leaving sticky ends . EcoRI and other restriction endonucleases are often used to cut DNA at specific sequences, before the fragments are put through gel electrophoresis and arranged by size, known as restriction digests of DNA. EcoRI is an example of a type II restriction enzyme. There is evidence that restriction enzymes of this type are evolutionarily related. There are differences in the codons used by E. coli and the condons that encode for EcoRi endonuclease and similarities between the amino acid sequence on EcoRI and other restriction endonucleases, such as RsrI, thus implying that the gene for EcoRI in E. coli could have been obtained by lateral gene transfer.