enzyme tag dna methyltransferase tag orchard PSI-MI MI:1186 2012-06-07T02:32:02Z The protein of interest is fused to Escherichia coli DNA adenine methyltransferase (dam). Expression of this fusion protein in vivo leads to preferential methylation of adenines in DNA surrounding the native binding sites of the dam fusion partner. Because adenine methylation does not occur endogenously in most eukaryotes, it provides a unique tag to mark protein interaction sites.