Figure 4

MutSα directs faithful repair of U•G mispairs in human nuclear extracts. (A) Representative reactions demonstrating repair of M13-U•G substrates by Ugi-treated LoVo nuclear extracts, in the absence (-) or presence (+) of 53 nM purified hMutSα. Arrows at left indicate unrepaired and repaired products; fraction of molecules repaired is shown below each lane. (B) Products of extension by pol η in the absence or presence of aphidicolin. Arrows at left indicate primer and extension product. (C) Representative reactions demonstrating repair of M13-U•G substrates by Ugi-treated HeLa or Ramos nuclear extracts, in the presence and absence of aphidicolin, which inhibits pol δ; PBP, the PCNA binding peptide, which inhibits PCNA; or exogenous ATP. Notations as in panel A.