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Methotrexate Inhibits Proteolysis of Dihydrofolate Reductase by the N-end Rule Pathway

Johnston, Jennifer A. and Johnson, Erica S. and Waller, Patrick R. H. and Varshavsky, Alexander (1995) Methotrexate Inhibits Proteolysis of Dihydrofolate Reductase by the N-end Rule Pathway. Journal of Biological Chemistry, 270 (14). pp. 8172-8178. ISSN 0021-9258. doi:10.1074/jbc.270.14.8172.

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The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. In eukaryotes, the N-end rule pathway is a ubiquitin-dependent, proteasome-based system that targets and processively degrades proteins bearing certain N-terminal residues. Arg-DHFR, a modified dihydrofolate reductase bearing an N-terminal arginine (destabilizing residue in the N-end rule), is short lived in ATP-supplemented reticulocyte extract. It is shown here that methotrexate, which is a folic acid analog and high affinity ligand of DHFR, inhibits the degradation but not ubiquitination of Arg-DHFR by the N-end rule pathway. The degradation of other N-end rule substrates is not affected by methotrexate. We discuss implications of these results for the mechanism of proteasome-mediated protein degradation.

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Varshavsky, Alexander0000-0002-4011-258X
Additional Information:© 1995 American Society for Biochemistry and Molecular Biology. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Received for publication, September 29, 1994, and in revised form, January 13, 1995. This work was supported in part by National Institutes of Health Grants DK39520 and GM31530 (to A. V.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Supported by a postdoctoral fellowship from the American Cancer Society. We thank David Gonda (Yale University) for helpful discussions, and members of this laboratory, especially Nils Johnsson and Michel Ghislain, for comments on the manuscript.
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American Cancer SocietyUNSPECIFIED
Issue or Number:14
Record Number:CaltechAUTHORS:20210211-152331800
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Official Citation:Jennifer A. Johnston, Erica S. Johnson, Patrick R.H. Waller, Alexander Varshavsky, Methotrexate Inhibits Proteolysis of Dihydrofolate Reductase by the N-end Rule Pathway, Journal of Biological Chemistry, Volume 270, Issue 14, 1995, Pages 8172-8178, ISSN 0021-9258,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108018
Deposited By: George Porter
Deposited On:12 Feb 2021 15:48
Last Modified:16 Nov 2021 19:08

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