The POLA1 gene (POLA1 stands for "DNA polymerase alpha 1, catalytic subunit") is a protein-coding gene, with the cytogenetic assignment: Xp22.11-p21.3.
The POLA1 gene encodes the catalytic subunit of DNA polymerase, which together with a regulatory and another two primase subunits forms the DNA polymerase alpha complex. This enzyme complex, which occurs in eukaryotes, is involved in the initiation of DNA replication. The DNA polymerase-alpha complex consists of 4 subunits: the catalytic subunit POLA1, the regulatory subunit POLA2 and the small and large primase subunits PRIM1 and PRIM2, respectively. Once the primase has generated the RNA primer, Pol alpha begins replication and extends the primer by about 20 nucleotides. The POLA1 catalytic subunit thus plays an essential role in the initiation of DNA replication.