“…[5] Numerous small organic groups such as ketone, [6] azides, [7] terminal alkynes, [8] and terminal alkenes, [9] as well as larger reactive bioorthogonal groups such as cyclooctyne, [10] norbornene, [11] transcyclooctene, [10b, 11b] tetrazole, [12] and tetrazine [13] have been genetically encoded for site-selective protein labeling in vivo. To track fast protein dynamics in vivo, it is imperative that these genetically encoded bioorthogonal reporters direct fast and selective bioorthogonal labeling with the cognate biophysical probes, preferably with a spatiotemporal control.…”