The latent endonuclease activity of MLH1:PMS2 (MutLalpha) is activated by interaction with MSH2:MSH3 (MutSbeta) (Zhang et al. 2005, and inferred from activation of MLH1:PMS2 by MSH2:MSH6). MLH1:PMS2 makes a nick in the strand of DNA that will be repaired (Kadyrov et al. 2006).
endonuclease activity of MLH1:PMS2:MSH2:MSH3:ATP:PCNA:DNA containing IDL of 2 bases or more [nucleoplasm]