Figure 3.

Effect of a single-base mismatch on end joining. (A) The 3-base 3′ overhang substrates shown were incubated in polλ-depleted extracts supplemented with various polymerases as in Figure 2, cut with BstXI and AvaI and analyzed on sequencing gels. (B) Proposed mechanisms of formation of 43- and 42-base products from the mismatched substrate. (C) Sequencing of repair joints in recircularized products. Sequences are expressed in terms of the radiolabeled (top) strand. Black and blue letters indicate sequences originating from the left and right ends of the break, respectively. Underlined nucleotides could have originated from either end and may have resulted from microhomology annealing and splicing. Overlines indicate apparent preservation of 3′ overhangs. The green letters in the last sequence begin 28 bases from the 5′ terminus of the right end. The first two sequences correspond to the two pathways shown in (B).