The DOI matches its Crossref record; 31 of the 31 references it cites were found in a registry or an index.
Isolation and expression of an altered mouse dihydrofolate reductase cDNA.
Open accessAbstract
We have constructed a cDNA library from a murine cell line expressing high levels of a dihydrofolate reductase (tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3) that displays an abnormally low affinity for methotrexate. From this library we have isolated a cDNA clone similar to, but distinguishable from, a cDNA clone previously demonstrated to encode the wild-type enzyme. Analysis of the nucleotide sequence of this cDNA clone allows us to predict that the altered dihydrofolate reductase differs from the wild-type enzyme at a single amino acid, reflecting the substitution of an arginine for a leucine residue in a region of the polypeptide thought to form a hydrophobic pocket essential for inhibitor binding. To confirm that this substitution was responsible for the altered properties of the enzyme, we genetically localized the region of the cDNA that specified resistance to methotrexate by in vitro recombination. These results reveal that a single nucleotide change in the codon specifying amino acid 22 of the enzyme was sufficient to alter the methotrexate sensitivity of the enzyme. We demonstrate that this altered gene can be employed as a dominant selectable marker in cultured cells expressing normal levels of wild-type dihydrofolate reductase.
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Cites
A rapid alkaline extraction procedure for screening recombinant plasmid DNA
Birnboim, H. C., & Doly, J. (1979) · Nucleic Acids Research · doi:10.1093/nar/7.6.1513 · Cited by 14,686
[57] Sequencing end-labeled DNA with base-specific chemical cleavages
Maxam, A. M., & Gilbert, W. (1980) · Methods in Enzymology · doi:10.1016/s0076-6879(80)65059-9 · Cited by 14,315
A new technique for the assay of infectivity of human adenovirus 5 DNA
Graham, F. L., & van der Eb, A. J. (1973) · Virology · doi:10.1016/0042-6822(73)90341-3 · Cited by 9,451
Colony hybridization: a method for the isolation of cloned DNAs that contain a specific gene.
Grunstein, M., & Hogness, D. S. (1975) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.72.10.3961 · Cited by 3,431
Southern, P. J., & Berg, P. R. (1982) · PubMed · Cited by 2,740
A system for shotgun DNA sequencing
Messing, J., Crea, R., & Seeburg, P. H. (1981) · Nucleic Acids Research · doi:10.1093/nar/9.2.309 · Cited by 2,619
Transformation of mammalian cells with genes from procaryotes and eucaryotes
Wigler, M., Sweet, R., Sim, G. K., Wold, B., Pellicer, A., Lacy, E., Maniatis, T., Silverstein, S., & Axel, R. (1979) · Cell · doi:10.1016/0092-8674(79)90093-x · Cited by 1,408
DNA-mediated transfer of the adenine phosphoribosyltransferase locus into mammalian cells.
Wigler, M., Pellicer, A., Silverstein, S., Axel, R., Urlaub, G., & Chasin, L. (1979) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.76.3.1373 · Cited by 1,279
Mulligan, R. C., & Berg, P. (1981) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.78.4.2072 · Cited by 982
Alt, F. W., Kellems, R. E., Bertino, J. R., & Schimke, R. T. (1978) · Journal of Biological Chemistry · doi:10.1016/s0021-9258(17)34875-5 · Cited by 941
Cited by
Burns, J. C., Friedmann, T., Driever, W., Burrascano, M., & Yee, J. K. (1993) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.90.17.8033 · Cited by 1,399
Chou, C. K., Dull, T. J., Russell, D. S., Gherzi, R., Lebwohl, D., Ullrich, A., & Rosen, O. M. (1987) · Journal of Biological Chemistry · doi:10.1016/s0021-9258(19)75716-0 · Cited by 640
Cloning of decay-accelerating factor suggests novel use of splicing to generate two proteins
Caras, I. W., Davitz, M. A., Rhee, L., Weddell, G., Martin, D. W., & Nussenzweig, V. (1987) · Nature · doi:10.1038/325545a0 · Cited by 351
Rosen, C. A., Sodroski, J. G., Goh, W. C., Dayton, A. I., Lippke, J., & Haseltine, W. A. (1986) · Nature · doi:10.1038/319555a0 · Cited by 323
Kokai, Y., Myers, J. N., Wada, T., Brown, V. I., LeVea, C. M., Davis, J. G., Dobashi, K., & Greene, M. I. (1989) · Cell · doi:10.1016/0092-8674(89)90843-x · Cited by 309
Metadata
- Authors
- Simonsen, C. C., & Levinson, A. D.
- Venue
- Proceedings of the National Academy of Sciences
- Published
- 1983-05
- Volume
- 80
- Issue
- 9
- Pages
- 2495-2499
- ISSN
- 0027-8424 (ISSN-L)
- 1091-6490
- OpenAlex
- W2042526641
- Cited by
- 417
- References
- 31
- FWCI
- 9.05
- Type
- journal article
- Language
- en
- Open access
- bronze
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Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).
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