Table 1.

The apparent equilibrium and kinetic binding parameters between H/ACA RNPs and substrate RNAs at 27°C

Substrate	H/ACA RNP	(103 M−1 s−1)	(10−3 s−1)	(µM)
Sub-Ud	WT	27 ± 1	n.d.	n.d.
Sub-U	D85A	17 ± 1	0.69 ± 0.09	0.031 ± 0.002
Sub-U	DEL7	18 ± 3	12 ± 3	0.23 ± 0.08
Sub-U	R154Q	11 ± 3	11 ± 2	0.47 ± 0.05
Sub-U	RNA only	n.d.	27 ± 5	1.5 ± 0.1
Sub-Ψ	WT	23 ± 5	12 ± 1	1.1 ± 0.2
Sub-Ψ	D85A	22 ± 4	11 ± 1	0.9 ± 0.1
Sub-Ψ	DEL7	15 ± 3	14 ± 1	0.9 ± 0.1
Sub-Ψ	R154Q	18 ± 8	16 ± 2	0.8 ± 0.1
Sub-Ψ	RNA only	n.d.	17 ± 5	1.72 ± 0.15
Sub-Ud	ΔGar1	12 ± 1	n.d.	n.d.
Sub-U	ΔGar1/D85A	26 ± 1	0.54 ± 0.04	0.036 ± 0.002
Sub-U	ΔGar1/DEL7	8.4 ± 0.4	7.8 ± 0.7	0.15 ± 0.01
Sub-U	ΔGar1/R154Q	8 ± 2	7 ± 1	0.42 ± 0.06
Sub-Ψ	ΔGar1	27 ± 5	5 ± 1	0.32 ± 0.04
Sub-Ψ	ΔGar1/D85A	35 ± 4	5 ± 1	0.20 ± 0.03
Sub-Ψ	ΔGar1/DEL7	22 ± 3	12 ± 1	0.7 ± 0.1
Sub-Ψ	ΔGar1/R154Q	24 ± 11	16 ± 4	0.83 ± 0.09
Sub-C	WT	n.d.	42 ± 9	3.5 ± 0.1

^aThe errors of k_on are from fitting.

^bk_off values are the mean ± SD from 2–3 independent measurements.

^cK_d values are the mean ± SD from 2–3 independent measurements.

^dThese substrate–enzyme combinations are reactive. Due to the fact that the concentrations of substrate and product RNAs vary with time, the apparent K_d and k_off would be time dependent and, therefore, cannot be determined by conventional analysis, n. d., not determined.