Does DNA polymerase I have exonuclease activity?

Yes! DNA polymerase I is an enzyme that has been extensively used in molecular biology, which is originally found to be a component in the process of prokaryotic DNA replication. The main physiological function of DNA polymerase I is to repair damaged DNA through its exonuclease activities. It has a 3’ to 5’ exonuclease activity that mediates proofreading, which lowers the error rate during DNA replication. Meanwhile, it also contains a 5’ to 3’ exonuclease activity, enabling the enzyme to replace nucleotides in the growing strand of DNA by nick translation.