Abstract
An activity in human cell extracts is described that repairs DNA with loops of five or more unpaired bases. Repair is strand-specific and is directed by a nick located 5' or 3' to the loop. This repair is observed in a colorectal cancer cell line that is devoid of a wild-type hMLH1 gene and is deficient in repair of mismatches. However, a cell line with deletions in both hMSH2 alleles is deficient in repair of both loops and mismatches. Defects in loop repair may be relevant to the repetitive-sequence instability observed in cancers and other hereditary diseases.
MeSH terms
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Adaptor Proteins, Signal Transducing
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Base Composition
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Base Sequence
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Carrier Proteins
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Cell Extracts
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Cell Line
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Colorectal Neoplasms / genetics*
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DNA Repair*
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DNA, Satellite / genetics
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DNA, Satellite / metabolism
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DNA-Binding Proteins*
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HeLa Cells
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Humans
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Molecular Sequence Data
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MutL Protein Homolog 1
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MutS Homolog 2 Protein
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Neoplasm Proteins / genetics*
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Neoplasm Proteins / physiology
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Nuclear Proteins
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Nucleic Acid Heteroduplexes / metabolism*
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Proto-Oncogene Proteins / genetics*
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Proto-Oncogene Proteins / physiology
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Repetitive Sequences, Nucleic Acid
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Tumor Cells, Cultured
Substances
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Adaptor Proteins, Signal Transducing
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Carrier Proteins
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Cell Extracts
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DNA, Satellite
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DNA-Binding Proteins
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MLH1 protein, human
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Neoplasm Proteins
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Nuclear Proteins
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Nucleic Acid Heteroduplexes
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Proto-Oncogene Proteins
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MSH2 protein, human
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MutL Protein Homolog 1
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MutS Homolog 2 Protein