DNA polymerase alpha (Pol alpha) (Pol alpha)

DNA polymerase alpha (Pol alpha) is a heterotetrameric enzyme complex essential for the initiation of DNA replication in eukaryotic cells (UniProt P09884). It consists of a catalytic subunit (POLA1), a regulatory subunit (POLA2), and two primase subunits (PRIM1 and PRIM2). The complex is unique in its ability to initiate DNA synthesis de novo by first creating a short RNA primer and then extending it with a short segment of DNA (PMID: 24835540). These RNA-DNA primers are subsequently elongated by the more processive DNA polymerases delta and epsilon during both leading and lagging strand synthesis. Because Pol alpha is indispensable for the S-phase of the cell cycle, it is a primary target for several chemotherapeutic nucleoside analogs, such as Cytarabine and Gemcitabine, which act as competitive inhibitors or chain terminators (PubMed: 11566128). Beyond its role in replication, POLA1 is involved in immune signaling; its deficiency leads to reduced cytosolic RNA-DNA hybrids, triggering an overproduction of Type I interferons (PMID: 26806125). This link to autoinflammatory diseases like X-linked reticulate pigmentary disorder highlights its broader biological significance beyond simple replication. In clinical settings, the inhibition of Pol alpha is a validated strategy for treating hematologic malignancies and solid tumors, though it is associated with significant side effects like myelosuppression.

Other names

POLA1DNA polymerase alpha-primase complexDNA polymerase alpha catalytic subunitp180 subunitDNA polymerase alpha 1

Inhibition of DNA synthesis through competitive inhibition with deoxyribonucleotide triphosphates (dNTPs) and/or DNA chain termination upon incorporation into the nascent DNA strand.