Table 1.

Mutational specificity of DNA polymerases κ and β

Region/mutational classa	Number of events (Proportion of region)
	pol κ	pol β
T11 microsatellite	28	16
T deletionb	0	12 (0.75)
T insertionc	4 (0.14)	1 (0.06)
G insertion	20 (0.71)	2 (0.12)
C insertion	2 (0.07)	0
Base substitutiond	2 (0.07)	1 (0.06)
HSV-tk coding	65	24
Base substitutions	9 (0.14)	3 (0.12)
Frameshiftse	53 (0.82)	19 (0.79)
Complex	3 (0.05)	2 (0.08)
HSV-tk− Mutant Frequencyf	24 × 10−4	35 × 10−4

^aMutations that create alleles longer than T₉ do not result in a mutant phenotype due to transcriptional slippage within the microsatellite.

^bIncludes −2T errors, −1T occurring as a multiple mutation, and complex errors involving the microsatellite.

^cIncludes + 1T errors occurring as a multiple mutation and complex errors involving the microsatellite.

^dBase substitution errors within the microsatellite occurred as multiple mutations.

^eAll frameshifts were deletion errors for both polymerases.

^fThe ssDNA mutant frequency is 1.3 × 10⁻⁴ for this template.