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Selective binding to DNA base pair mismatches by proteins from human cells
1Imperial Cancer Research Fund, Clare Hall Laboratories, Potters Bar, Hertfordshire, United Kingdom.
The Journal of Biological Chemistry
|December 15, 1989
Summary
Researchers found proteins in human cell extracts that bind to mismatched DNA bases. This discovery suggests a new DNA repair pathway for correcting single base errors in human cells.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- DNA mismatches can arise from replication errors or DNA damage.
- Efficient repair mechanisms are crucial for maintaining genomic stability.
Purpose of the Study:
- To identify and characterize DNA mismatch binding proteins in human cell extracts.
- To investigate the role of these proteins in DNA repair pathways.
Main Methods:
- Delayed oligonucleotide migration assay using polyacrylamide gel electrophoresis.
- Analysis of cell-free extracts from human cell lines (Raji, HeLa, lymphoblastoid, MRC5V1).
Main Results:
- Identified proteins in Raji cell extracts that bind to single base pair DNA mismatches.
- Characterized two distinct mismatch binding activities: one recognizing G.T mismatches, and a novel activity recognizing A.C, T.C, and T.T mismatches.
- The novel mismatch binding protein is present in various human cell types, including those from normal individuals and xeroderma pigmentosum patients.
Conclusions:
- Human cells possess proteins capable of recognizing and binding to various DNA mismatches.
- A novel mismatch binding protein suggests a broad-specificity DNA repair pathway for single base mismatches.
- This pathway likely plays a significant role in maintaining genome integrity in human cells.