Pol α (alpha) synthesizes the RNA primers during initiation. Then, in a process called polymerase switching, it is replaced by Pol δ (delta), which performs the main task of concurrent elongation of both strands.

Pol ε (epsilon) is the other enzyme involved in nuclear DNA synthesis, possibly playing a role in binding to the origin or synthesis of the lagging strand.

Pol γ (gamma) is encoded by a nuclear gene though its function is synthesis of mitochondrial DNA.