DNA polymerase alpha

DNA Polymerase Alpha (DNA Pol α) is a type of DNA polymerase that plays a crucial role in DNA replication and DNA repair in eukaryotes. It is a multi-subunit enzyme complex that includes a catalytic core of two subunits, Pol1 and Pol2, and two additional subunits, Pol12 and Cdc27.

Function

DNA Pol α is responsible for the initiation of DNA replication. It synthesizes a short RNA primer (about 10 nucleotides long) which is extended by a DNA segment of 10-20 nucleotides. This RNA-DNA hybrid serves as a primer for DNA polymerase delta and DNA polymerase epsilon, which carry out the bulk of DNA synthesis.

Structure

The DNA Pol α complex is composed of four subunits. The Pol1 and Pol2 subunits form the catalytic core. Pol1 has the polymerase activity while Pol2 has the 3'-5' exonuclease activity. The Pol12 and Cdc27 subunits are regulatory and have roles in the interaction with other proteins and in the stability of the complex.

Role in DNA Repair

In addition to its role in DNA replication, DNA Pol α is also involved in DNA repair processes. It participates in base excision repair (BER), a process that corrects small, non-helix-distorting base lesions in the DNA.

Clinical Significance

Alterations in the function of DNA Pol α can lead to genomic instability and contribute to the development of cancer. Inhibitors of DNA Pol α, such as aphidicolin, are used in cancer research to study the role of this enzyme in DNA replication and repair.

File:DNA polymerase alpha.png

Structure of DNA polymerase alpha.

See Also

• DNA polymerase delta
• DNA polymerase epsilon
• DNA replication
• DNA repair
• Base excision repair

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