Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 7, 1995 | Published
Journal Article Open

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


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.

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.

Attached Files

Published - J._Biol._Chem.-1995-Johnston-8172-8.pdf


Files (965.2 kB)
Name Size Download all
965.2 kB Preview Download

Additional details

August 20, 2023
October 23, 2023