Table 1.

Effects of Mutations on Coat Protein RNA Binding

NT	A	G	U	C
1	1	2	2	2
2	100	100	1	0.18
3	1	1000	1000	1000

NT labels the nucleotide number in Fig. 1d which, when altered according to the table, changes the dissociation constant K_D by the factor listed. Mutations to multiple nucleotide positions affect K_D in a multiplicative manner. Estimates for the dissociation constant are based on experimental data for bacteriophage MS2 (see (30) and (6)).