However, both DNA polymerase αand DNA polymerase δ are now known to take part in eukaryotic DNA replication (see later for details). DNA polymerase αhas four subunits and an appropriate designation for this enzyme is DNA polymerase α/primase. Three other enzymes which are found associated with large DNA polymerase αinclude thymidine kinase, ribonucleotide reductase and thymidylate synthetase. They are also believed to be involved in DNA replication.
Nuclear small DNA polymerase βresembles large DNA polymerase αin its replicative activity, but differs in some other respects. Its quantity remains unchanged, while that of large polymerase changes with need. It is speculated that small enzyme may be involved in repair and recombination. The differences between these polymerases are shown in Table 26.2.
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