Table 1.

Equilibrium dissociation constants for interaction of nucleotides with PKR.^a

Nucleotide	Enzyme Form
	Unphosphorylated	Phosphorylated	K296R Mutant	Unphos. + 40mer dsRNA
mant-AMPPNP	33.8 ± 0.7b 34.8 ± 3.6c	34.0 ± 0.7b	11.5 ± 0.3b	102.3 ± 3.6c
mant-ATP	-	24.6 ± 1.7c	10.3 ± 0.8b	-
ATP	-	24.4 ± 0.1d	20.2 ± 1.7d	-
AMPPNP	97.7 ± 1.7d	34.0 ± 0.1d	22.8 ± 2.0d	160.5 ± 1.4d
ADP	76.5 ± 1.1d	11.6 ± 0.7d	12.5 ± 0.3d	67.0 ± 0.7d

^aK_d values in units of μM.

^bForward anisotropy titration.

^cReverse anisotropy titration.

^dCompetition titration using mant-AMPPNP.