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Research background and purpose of the DNA polymerase (DNA polymerase) was first discovered in E. coli by Kornberg (Kornberg) 1956 , also known as Kornber enzyme . Later the other prokaryotes and microbial discovered its existence . Currently known DNA polymerases are a large family of at least 14 species of DNA polymerase so far in eukaryotes , comprising polymerase, an α, β , γ , δ , ε, ζ, η, θ , Ι , κ , and λ , μ, REV1, MUS308. Their replication, repair of DNA in eukaryotic cells , play an important role in the cross injury synthesis , DNA recombination , and cell cycle regulation of a variety of important biological metabolic processes . DNA polymerase beta is a single peptide chain of small molecule protein isolated from bovine thymus cells , Weissbach et al , widely found in the nucleus of mammals . DNA polymerase β is considered to be a housekeeping gene , is highly conserved from yeast to mammalian cells . The gene encoding the single copy of the human cell DNA polymerase beta exist in 8P12-P11, the total length of 35Kb, consists of 14 exons and 13 introns . The primary structure of a polypeptide consisting of 335 amino acids , is currently known of the polymerase in the smallest molecular weight . For the pathogenesis of malignant tumors , previous studies have mostly concentrated on mutations in oncogenes and tumor suppressor genes , however, caused the initial molecular defects in these gene mutations accumulated into tumors is not yet clear . With the progress of molecular biology , it is successively found in colorectal cancer , prostate cancer , stomach cancer, breast cancer , lung cancer , kidney cancer , bladder cancer , and esophageal cancer gene mutations polβ , the attendant polβ gene and tumor relationship growing cause for concern . The study found that , DNA polymerase β in mammalian cells involved in a certain process of DNA synthesis and repair , they may be monitoring errors of DNA damage DNA fragment excised , repair, good notch of DNA , thus ensuring the stability of DNA , prevents mutations lead to cell mutations and tumor formation . Eca109, Eca9706 and NIH3T3 were derived from poorly differentiated and well-differentiated esophageal squamous cell carcinoma , and the edge lines of mouse fibroblasts cell lines . Three
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