Table 1.

Characteristics of vector-based systems for RNA live imaging. Affinity is presented as K_D (dissociation constant) – the propensity of a complex to dissociate into parts. Legend: * - Eukaryota/Prokaryota, ** - threshold not estimated, ‘-’ - not applicable, NA - not analyzed, app. – approximately, ? - not specified by authors. Unless stated otherwise, data were obtained from studies cited in the systems description paragraph

		RNA-dye systems
Name Feature	MS2	λN22	BglG	PP7	U1Ap	HTLV-1 Rex	TAT-TAR	REV-RRE	eiF4A	Spinach	Spinach2	Malachite Green	SRB-2
RNA size	19 nt	15 nt	29 nt	25 nt	21 nt	36 nt	23 nt?38	30 nt?38	58 nt	98 nt	95 nt	38 nt	54 nt
number of hairpins	1–96	1–25	18	1–24	4–16	1	1	1	2	1	1	1	1
number of hairpins required for single molecule imaging	24/96*	≤12**	≤18**	≤24 **	NA	NA	NA	NA	NA	NA	NA	NA	NA
minimal peptide size used (aa)	117	22	58?20	128	94	16	9–86?38	14–116?38	215 +191	—	—	—	—
protein dimerization	YES	NO	NO	YES	NO	NO	NO	NO	—	—	—	—	—
affinity of ligands to the aptamer(KD)	5 nM	22 nM	NA	1 nM	< 1 nM?33	30 nM	0.31–2.1 nM?40	1–3 nM?39	44 nM	450 nM	430 nM	110 nM–1.8 μM	1.4 ± 0.1 μM
BiFC	NO	NO	NO	NO	NO	NO	NO	NO	YES	—	—	—	—
background problem	YES	YES	YES	YES	YES	YES	YES	YES	NO	NO	NO	NO	NO
comment	—	—	BglG is a bacterial protein	—	U1Ap is a human protein	—	Only tested in TriFC experi-ment	Only tested in TriFC experi-ment	eiF4A is a murine protein	thermal instability	+ tRNA sequence	—	+ tRNA sequence