Eukaryotic DNA Polymerases

Mammalian cells contain four distinct DNA polymerases, while yeast cells contain at least five - , , , , and . A short summary of the properties of each enzyme is as follows:

> - Distinctive for containing a primase activity, it is also highly sensitive to an inhibitor called aphidicolin. Functions in lagging strand synthesis.

> - It has low processivity (i.e., it does not polymerize DNA for long periods of time). Functions in DNA repair. Low sensitivity to aphidicolin.

> - A mitochondrial DNA polymerase. Low sensitivity to aphidicolin.

> - It may be the principal leading strand polymerase. Requires a protein called proliferating cell nuclear antigen (PCNA) to carry out highly processive DNA synthesis in vitro. PCNA functions like the clamp of E. coli DNA Polymerase III holoenzyme.

> - Its function is not yet completely clear.

Table 24.3 also summarizes some known properties and cellular locations of these enzymes.

See also: E. coli DNA Polymerases, Other Replication Proteins, Replication Complexes

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