DNA polymerase

DNA polymerase (Dpo) reads a DNA strand and catalyzes the synthesis of its complementary strand. Dpo's are divided into 7 families according to their sequence homology and 3D structure similarities.^[1] The families are:

• Family A - replicative or repair Dpo.
  
• Family B - replicative Dpo involved in processing DNA replication during cell division (includes eukaryotic Dpo α,δ,ε).
  
• Family C - major replicative Dpo in bacteria (includes Dpo II, III, IV).
  
• Family D - replicative. Present in archaea.
  
• Family X - eukaryotic repair Dpo (includes Dpo β,λ,σ,μ and terminal deoxynucleotidyl transferase).
  
• Family Y - replicative of damaged DNA (includes eukaryotic η,ι,κ).
  
• Family RT - reverse transcriptase. See Reverse transcriptase.
  

Some Dpo terminology:
Dpo sliding clamp is made of the complex of Dpo and Proliferating Cell Nuclear Antigen (PCNA) which encircles it.
The BRCT domain in Dpo is the C-terminal domain of breast cancer susceptibility protein.
Klenow fragment is a large Dpo fragment produced upon cleavage of Dpo by subtilisin.
In the E. coli, the EcDpo III subunits β, γ, δ, δ' are named clamp loader. This complex assembles the β subunit sliding clamp unto the DNA.

Prokaryotic DNA polymerases:

• DNA polymerase I: involved in excision repair. Major polymerase in E. coli. For more details see DNA Polymerase I. See also Taq DNA polymerase (Hebrew).
  
• DNA polymerase II: active in replication forks.
  
• DNA polymerase III: involved in DNA replication. For more details see Polymerase III homoenzyme beta subunit and Alpha Subunit of Thermus aquaticus DNA Polymerase III.
  
• DNA polymerase IV: involved in non-targeted mutagenesis.
  
• DNA polymerase V: involved in translesion synthesis.
  

Eukaryotic DNA polymerases:

• Pol α,β,γ,δ,ε,ζ,η,ι,κ. See also DNA polymerase beta.
  
• Rev1 is a Dpo involved in replication over DNA lesions.
  
• Terminal deoxynucleotidyl transferase (TdT) is a family X Dpo expressed in immature lymphoid cells. TdT adds nucleotides to exons during antibody gene recombination.
  

See also User:Karl E. Zahn/RB69 DNA polymerase (gp43)