Identification and characterization of human DNA polymerase beta 2, a DNA polymerase beta -related enzyme

J Biol Chem. 2000 Oct 6;275(40):31233-8. doi: 10.1074/jbc.M004263200.


The BRCA1 COOH terminus (BRCT) motif is present in many nuclear proteins that contribute to cell cycle regulation or DNA repair. Polymerase chain reaction-based screening with degenerate primers targeted to the BRCT motif resulted in the isolation of a human cDNA for a previously unidentified DNA polymerase (designated DNA polymerase beta2) that is closely related to DNA polymerase beta (Pol beta). The predicted Pol beta2 protein contains a BRCT motif in its NH(2)-terminal region; its COOH-terminal region exhibits 33% sequence identity to a corresponding region of human Pol beta. The Pol beta2 gene is expressed in a tissue-specific manner, with transcripts being most abundant in testis. A fusion construct comprising Pol beta2 and green fluorescent protein exhibited a predominantly nuclear localization in transfected HeLa cells. Recombinant human Pol beta2 from insect cells exhibited substantial DNA polymerase activity, but it did not possess terminal deoxyribonucleotidyl transferase activity. A truncated Pol beta2 mutant lacking the BRCT motif retained substantial DNA polymerase activity, whereas a mutant Pol beta2 with two alanine point mutations within the DNA polymerase active site did not. These results indicate that Pol beta2 is a Pol beta-related DNA polymerase with a BRCT motif that is dispensable for its polymerase activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Blotting, Northern
  • Cell Line
  • Cell Nucleus / metabolism
  • Cloning, Molecular
  • DNA Nucleotidylexotransferase / metabolism
  • DNA Polymerase beta / chemistry*
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / metabolism*
  • Green Fluorescent Proteins
  • HeLa Cells
  • Humans
  • Immunoblotting
  • In Situ Hybridization, Fluorescence
  • Insecta
  • Luminescent Proteins / metabolism
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Tissue Distribution


  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • DNA polymerase beta2
  • DNA Nucleotidylexotransferase
  • DNA Polymerase beta