Table 2.

Base-substitution error specificity of Y265C and β-WT in the λcII assay

Base-substitution class	Mispair*	Frequency × 10−5 (no. observed)
		Y265C	β-WT	Y265C/β-WT†
GC → AT	G:T or C:A	47  (31)‡	3.1  (15)§	15
GC → TA	C:T or G:A	6.2  (4)¶	2.9  (14)‖	2.1
AT → GC	A:C or T:G	6.2  (4)	1.8  (9)	3.4
GC → CG	G:G or C:C	3.0  (2)	0.4  (2)	7.5
TA → GC	T:C or A:G	3.0  (2)	0.2  (1)	15
TA → AT	T:T or A:A	1.5  (1)	0.2  (1)	7.5
Total**		44	42

^*A mispair that could be formed by the Y265C or β-WT polymerase. 

^†The frequency of mutations arising from expression of Y265C divided by the frequency of mutations arising from expression of β-WT. 

^‡Twenty-three of 31 transitions are at CpG dinucleotides. 

^§Twelve of 15 transitions are at CpG dinucleotides. 

^¶Three of 4 transversions are at CpG sites. 

^‖Two of 14 transversions are at CpG sites. 

^**Total number of base-substitution mutations.