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. 2013 Feb 26;8(2):e56960. doi: 10.1371/journal.pone.0056960

Figure 4. CTG repeat instability resulting from an abasic lesion at the 3′-end of (CTG)20 repeats.

Figure 4

(A) A substrate containing (CTG)20 repeats with a THF that substituted the guanine of the twentieth CTG was incubated with 60 µg cell extracts of pol β−/− or pol β+/+ MEFs (panels B and C ) for 30 min. Panel A represents the result of PCR amplification of a DNA marker with (CTG)20 repeats. Panel D represents the quantitative analysis of the results of panels B and C. (B) The repair of a THF at the 3′-end of (CTG)20 repeats was performed by BER reconstituted with 10 nM purified pol β (panel B). Panel A is the result of PCR amplification of a (CTG)20 repeat-containing marker without any DNA damage. Substrates were 32P-labeled at the 5′-end of the damaged strand as indicated. Size standards are indicated.