PROSITE documentation PDOC51157
Zinc finger UBR-type profile


It has been observed that the identity of N-terminal residues of a protein is related to the half life of the protein. This observation yields a rule, called the N-end rule [1]. Similar but distinct versions of the N-end rule operate in all organisms examined, from mammals to fungi and bacteria. In eukaryotes, the N-end rule pathway is a part of the ubiquitin degradation system. Some proteins that have a very short half life contain a specific motif at their N-terminus, the N-degron. It consists of a destabilizing N-terminal residue and an internal Lys, which is the site of poly-Ub chain [1,2].

The UBR1 protein was shown to bind specifically to proteins bearing N-terminal residues that are destabilizing according to the N-end rule, but not to otherwise identical proteins bearing stabilizing N-terminal residues [3]. UBR1 contain an N-terminal conserved region (the UBR-type zinc finger) which is also found in various proteins implicated in N-degron recognition. The UBR-type zinc finger defines a unique E3 class, most likely N-degron specific [4].

The profile we developed covers the whole UBR-type zinc finger.


The UBR-type zinc finger is also known as the UBR box motif [4].

Last update:

October 2005 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ZF_UBR, PS51157; Zinc finger UBR-type profile  (MATRIX)


1AuthorsVarshavsky A.
TitleThe N-end rule: functions, mysteries, uses.
SourceProc. Natl. Acad. Sci. U.S.A. 93:12142-12149(1996).
PubMed ID8901547

2AuthorsSuzuki T. Varshavsky A.
TitleDegradation signals in the lysine-asparagine sequence space.
SourceEMBO J. 18:6017-6026(1999).
PubMed ID10545113

3AuthorsXie Y. Varshavsky A.
TitleThe E2-E3 interaction in the N-end rule pathway: the RING-H2 finger of E3 is required for the synthesis of multiubiquitin chain.
SourceEMBO J. 18:6832-6844(1999).
PubMed ID10581257

4AuthorsTasaki T. Mulder L.C. Iwamatsu A. Lee M.J. Davydov I.V. Varshavsky A. Muesing M. Kwon Y.T.
TitleA family of mammalian E3 ubiquitin ligases that contain the UBR box motif and recognize N-degrons.
SourceMol. Cell. Biol. 25:7120-7136(2005).
PubMed ID16055722

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