question: What is the basis of the DamID experimental protocol?
answer:  Dam Identification (DamID) system induced by Cre recombinase using Lamin B1 and mouse embryonic fibroblasts. This inducible system will help to generate genome-wide profiles of chromatin proteins in given cell types and tissues with no need to dissect tissues from organs or separate cells from tissues, which is achieved by using specific regulatory DNA elements and due to the high sensitivity of the method. DNA adenine methyltransferase identification (DamID) has emerged as one of the most comprehensive and versatile methods available for profiling protein-DNA interactions on a genomic scale.  Recently, a novel methylation-based tagging technique, termed DamID (DNA adenine methyltransferase identification), has emerged as a powerful tool to decipher transcriptional networks, to study chromatin-associated proteins, and to monitor higher-order chromatin organization on a genome-wide scale. We show here that the in vivo methylation-based tagging technique DamID (DNA adenine methyltransferase identification) can be used for studies of DNA-protein interactions or chromatin profiling in plants DamID is a powerful method used to map the genomic interaction sites of these proteins in vivo  It is based on fusing a protein of interest 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. DNA adenine methyltransferase identification (DamID) is an enzymatic technology for detecting DNA regions targeted by chromatin-associated proteins.  Overall, DamID is highly robust: while the orientation of WT Dam fusions can affect the size of the target sets, their signatures remained largely reproducible.  