Tag:oDam corresponds to an optimized version of the DNA adenine methyltransferase encoded by the Escherichia coli Dam gene (ECOGENE:EG10204). In addition to codon optimization, it contains a L122A mutation and cryptic splicing regulatory sites have been removed (PMID:27707796). The L122A mutation has been shown to increase the specificity of methylation on the GATC target site, due to a loss of ability to methylate noncanonical near-cognate sites (PMID:15882618). When fused to a chromatin-associated protein, Tag:oDam can targeted in vivo to the native binding sites of the tagged protein, resulting in local DNA methylation in the vicinity of these binding sites. The methylation sites can subsequently be identified using either methylation-specific restriction enzymes or antibodies, permitting identification of sequences that interact in vivo with the tagged protein.