Table 4. Overview of bioorthogonally protected unnatural amino acids tested in mammalian cell systems and their deprotection conditions.

Amino acid		System	Proteins	Reaction	Reagent
		HeLa, CHO, HEK293T, IH3T3, Caco-2, A549, HeLa	GFP, OspF phosphothreonine lyase	Pd-catalysed Tsuji–Trost-like reaction	Pd(II) complexes [57]
		HEK293T	eGFP, SATB1 transcription factor, Cre recombinase, Cas9 endonuclease	Staudinger	Various phosphines [63]
		HEK293T	eGFR, luciferase, OspF phosphothreonine lyase, Src kinase	1,3-dipolar cycloaddition	trans-cyclooctenes [62]
		HEK293T	GFP [61], Luciferase [59,61], MEK1 [18,60] and MEK2 [18] and FAK [60] and Src [60] kinases	Inverse electron demand Diels–Alder reactions	Tetrazines [18,59–61]