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Updated: Jul 18, 2026

Analysis of DNA Double-strand Break (DSB) Repair in Mammalian Cells
Published on: September 8, 2010
The human DINB1 gene encodes the DNA polymerase Poltheta
R E Johnson1, S Prakash, L Prakash
1Sealy Center for Molecular Science, University of Texas Medical Branch, 6.014 Medical Research Building, 11th & Mechanic Streets, Galveston, TX 77555-1061, USA.
Abstract:
The human DINB1 gene shares a high degree of homology with the Escherichia coli dinB gene. Here, we purify the hDINB1-encoded protein and show that it is a DNA polymerase. Because hDinB1 is the eighth eukaryotic DNA polymerase to be described, we have named it DNA polymerase (Pol) theta. hPoltheta is unable to bypass a cis-syn thymine-thymine dimer, nor does it bypass a (6-4) photoproduct or an abasic site. We also examine the fidelity of hPoltheta on nondamaged DNA templates by steady-state kinetic analyses and find that hPoltheta misincorporates deoxynucleotides with a frequency of about 10(-3) to 10(-4). We discuss the relationship between the fidelity of hPoltheta and its inability to bypass DNA damage.
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