The Choice Between Long-patch and Short-patch Repair
The choice between short- and long-patch repair is currently under investigation. Various factors are thought to influence this decision, including the type of lesion, the cell cycle stage, and whether the cell is terminally differentiated or actively dividing. Some lesions, such as oxidized or reduced AP sites, are resistant to pol β lyase activity and, therefore, must be processed by long-patch BER.
Pathway preference may differ between organisms, as well. While human cells utilize both short- and long-patch BER, the yeast Saccharomyces cerevisiae was long thought to lack a short-patch pathway because it does not have homologs of several mammalian short-patch proteins, including pol β, DNA ligase III, XRCC1, and the kinase domain of PNKP. The recent discovery that the poly-A polymerase Trf4 possesses 5' dRP lyase activity has challenged this view.
Read more about this topic: Base Excision Repair
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