Catalytic component of DNA polymerase alpha, which in complex with DNA primase (DNA polymerase alpha:primase) constitutes a replicative polymerase (PubMed:10898792, PubMed:22119860, PubMed:31488849). POL1 has a role in promoting telomere replication during interaction with CDC13 (PubMed:10898792). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) DNA polymerase alpha:primase is a four subunit enzyme complex, which is assembled throughout the cell cycle, and consists of the two DNA polymerase subunits A POL1 and B POL12, and the DNA primase large PRI2 and small PRI1 subunits (PubMed:3061469). Subunit B POL12 binds to subunit A POL1 (PubMed:19494830). POL1 interacts with CDC13, POB3, SPT16 and MCM10 (PubMed:10898792, PubMed:16675460, PubMed:8621497, PubMed:9199353). The CysA-type zinc finger is required for PCNA-binding. In eukaryotes there are five DNA polymerases: alpha, beta, gamma, delta, and epsilon which are responsible for different reactions of DNA synthesis. Present with 1050 molecules/cell in log phase SD medium. Belongs to the DNA polymerase type-B family. A structure shows that CysB motif binds zinc but a later study has suggested it might bind 1 4Fe-4S cluster instead.