ID #1244

I was just looking over the mismatch repair and had a quick question. After the cut is made in the unmethylated strand, a 5'3' exonuclease activity must come in in order to digest the nonmethylated strand (because that is the direction it grew in), correct?

Based on the figure I showed in class, this is exactly the conclusion that you should come to. One thing that changes the situation slightly is that the nearest GATC sequence might lie on the "other" side of the mistake. In that case, everything in that figure would still be true, it would just be reversed. So in that case, the exonuclease that you'd need to strip out that region would be a 3'-5' exonuclease. The mismatch repair system has both, just in case!

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