Fig. 3: MutSβ, MutLγ, RPA, RFC, PCNA and Polδ catalyze repeat expansion.
From: Mechanism of trinucleotide repeat expansion by MutSβ-MutLγ and contraction by FAN1
a A model for trinucleotide repeat expansion. b A representative of three independent DNA strand displacement assays. pSam_(CAG)4 DNA was nicked by MutSβ and MutLγ, and the reaction was then supplemented with Polδ, RPA, RFC and PCNA. Strand displacement DNA synthesis was detected by the incorporation of radioactive dCTP into high molecular weight DNA. c pSam_(CAG)4 DNA was reacted with the indicated proteins, followed by Sanger and TIDER analysis of the reaction products. While no modification of the looped strand was observed, a fraction of the opposite strand contained an insertion of the (CTG)4 sequence, supporting the model depicted in (a). The p-value associated with the trace signal is computed using a two-tailed t test, with the standard errors derived from the variance-covariance matrix. Source data are provided as a Source Data file.
