MMR in Mammalian Cells

It is generally held that it is likely that the signal for strand discrimination in mammalian MMR and perhaps many other organisms as well is provided by the DNA termini that are present in the strands of nascent DNA in the replication fork. The terminus that the DNA polymerase is in the process of extending also provides an entry site for the helicase to displace the strand and Exol to degrade the strand. What is unclear is how communication is achieved between the site of the mismatch and the terminus that is being extended by the DNA polymerase because these may be several thousand base pairs away from each other. There are several models currently under hot debate. One model proposed by Rick Fishel is called the 

Initiation Excision MutSa, MutS 3, MutLa HMGB1 

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