What is the main DNA polymerase?

In eukaryotic cells, DNA polymerase δ is the primary enzyme involved in DNA replication in eukaryotic cells. Polymerase δ plays a crucial role in DNA replication by synthesizing both the leading and lagging strands. It extends the RNA-DNA primers that are first synthesized by the polymerase α-primase complex. Additionally, it possesses 3’→5’ exonuclease activity, enabling it to correct errors during DNA synthesis by proofreading. Another major polymerase is DNA polymerase α, which primarily functions to synthesize primers during DNA replication. Its smaller subunit possesses primase activity, while the largest subunit handles polymerization. This DNA polymerase synthesizes short RNA-DNA fragments during the synthesis of the lagging DNA strand.

In prokaryotes, polymerase III is the major replicative polymerase, as it is involved in the synthesis of both the leading strand of DNA and of Okazaki fragments by the extension of RNA primers. Following this, DNA polymerase I removes the RNA primers and fills the gaps between Okazaki fragments.