Mapping N6‐Methyladenosine (m6A) in RNA: Established Methods, Remaining Challenges, and Emerging Approaches

Abstract N 6 ‐Methyladenosine (m 6 A) is the most abundant internal modification in eukaryotic mRNA. Specific m 6 A reader and eraser proteins link this modification to many aspects of mRNA metabolism and regulate its levels in a dynamic way. Precise localization and quantification in varying biological samples is, therefore, relevant to understand the functional role of m 6 A and mechanisms governing its regulation. In this Minireview, we summarize established and emerging concepts for m 6 A mapping. Starting with the seminal m 6 A‐sequencing techniques based on immunoprecipitation, we will highlight technical improvements by photo‐cross‐linking and remaining challenges. As an alternative, antibody‐free approaches will be presented. These include wild‐type or engineered m 6 A‐sensitive enzymes and chemical biology approaches combining substrate analogues, chemical derivatization, and enzymatic steps to trace m 6 A. Finally, single‐molecule sequencing as a new avenue for direct detection of mRNA modifications will be discussed.