A Caltech Library Service

Bivalent Inhibitor of the N-end Rule Pathway

Kwon, Yong Tae and Lévy, Frédéric and Varshavsky, Alexander (1999) Bivalent Inhibitor of the N-end Rule Pathway. Journal of Biological Chemistry, 274 (25). pp. 18135-18139. ISSN 0021-9258. doi:10.1074/jbc.274.25.18135.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Ubr1p, the recognition (E3) component of the Saccharomyces cerevisiae N-end rule pathway, contains at least two substrate-binding sites. The type 1 site is specific for N-terminal basic residues Arg, Lys, and His. The type 2 site is specific for N-terminal bulky hydrophobic residues Phe, Leu, Trp, Tyr, and Ile. Previous work has shown that dipeptides bearing either type 1 or type 2 N-terminal residues act as weak but specific inhibitors of the N-end rule pathway. We took advantage of the two-site architecture of Ubr1p to explore the feasibility of bivalent N-end rule inhibitors, whose expected higher efficacy would result from higher affinity of the cooperative (bivalent) binding to Ubr1p. The inhibitor comprised mixed tetramers of beta-galactosidase that bore both N-terminal Arg (type 1 residue) and N-terminal Leu (type 2 residue) but that were resistant to proteolysis in vivo. Expression of these constructs in S. cerevisiae inhibited the N-end rule pathway much more strongly than the expression of otherwise identical beta-galactosidase tetramers whose N-terminal residues were exclusively Arg or exclusively Leu. In addition to demonstrating spatial proximity between the type 1 and type 2 substrate-binding sites of Ubr1p, these results provide a route to high affinity inhibitors of the N-end rule pathway.

Item Type:Article
Related URLs:
URLURL TypeDescription
Varshavsky, Alexander0000-0002-4011-258X
Additional Information:© 1999 by The American Society for Biochemistry and Molecular Biology, Inc. (Received for publication, February 9, 1999) We thank members of the Varshavsky laboratory, especially A. Kashina and G. Turner, for helpful discussions and advice in the course of this work. We also thank I. Davydov, F. Du, F. Navarro-Garcia, H. Rao, and especially G. Turner for comments on the manuscript. This work was supported by National Institutes of Health Grant DK39520 (to A. V.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Funding AgencyGrant Number
Issue or Number:25
Record Number:CaltechAUTHORS:KWOjbc99
Persistent URL:
Official Citation:Yong Tae Kwon, Frédéric Lévy, and Alexander Varshavsky Bivalent Inhibitor of the N-end Rule Pathway J. Biol. Chem. 1999 274: 18135-. doi:10.1074/jbc.274.25.18135
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6413
Deposited By: Archive Administrator
Deposited On:07 Dec 2006
Last Modified:08 Nov 2021 20:33

Repository Staff Only: item control page