Which polymerase in eukaryotes is known for its involvement in base excision repair?

DNA Polymerase β plays a crucial role in base excision repair (BER) in eukaryotic cells. This polymerase is specifically adapted to fill in the gaps left by the removal of damaged bases. During the BER process, DNA glycosylases first recognize and remove damaged bases, creating an abasic site. Subsequently, apurinic/apyrimidinic (AP) endonuclease cuts the DNA backbone at this site, allowing for the removal of the sugar-phosphate residue. DNA Polymerase β is then recruited to this gap to synthesize the correct nucleotides to restore the DNA strand. Its activities are vital for maintaining genomic stability by repairing oxidative and alkylative damage to bases, which are common sources of DNA lesions.

The other polymerases, while important in various DNA replication and repair processes, do not specifically carry out the tasks associated with base excision repair. For instance, DNA Polymerase α primarily initiates DNA synthesis, while DNA Polymerase δ and ε are mainly involved in the elongation of the newly synthesized DNA during replication. Therefore, DNA Polymerase β is uniquely positioned and specifically tailored to function in the base excision repair pathway.