2-(Azidomethyl)nicotinic acid imidazolide (NAI-N3) is an RNA icSHAPE probe for live-cell RNA structure profiling across the genome. icSHAPE -- or in vivo click selective 2′-hydroxyl acylation and profiling experiment -- uses NAI-N3 in a chemoaffinity method to probe RNA structure. NAI-N3 is an azido version of the cell-permeable SHAPE reagent 2-methylnicotinic acid imidazolide (NAI) that permits the tagging of NAI-N3-modified RNA with a biotin moiety for subsequent capture via streptavidin. Not only do such strategies further the understanding of RNA structure in living cells but also provide a tool for identifying regions that may be susceptible to therapeutic targeting. Recently, the azidomethylnicotinyl (AMN) group of NAI-N3 was demonstrated to block the function of gRNA and CRISPR systems, which could be reactivated by removing the AMN groups with Staudinger reduction (DPBM phosphine), overall providing a means to control nucleic acid cleavage and gene editing in live cells.