PROSITE documentation PDOC00463
Ubiquitin-activating enzyme signatures


Ubiquitin-activating enzyme (E1 enzyme) [1,2] activates ubiquitin by first adenylating with ATP its C-terminal glycine residue and thereafter linking this residue to the side chain of a cysteine residue in E1, yielding an ubiquitin-E1 thiolester and free AMP. Later the ubiquitin moiety is transferred to a cysteine residue on one of the many forms of ubiquitin-conjugating enzymes (E2).

E1 is a large monomeric protein of about 110 to 115 Kd (about 1000 residues). In yeast there are two forms (UBA1 and UBA2) [3], while in plants and mammals multiple forms exist including a form which is Y-linked in mouse and some other mammals and which may be involved in spermatogenesis.

It has been shown [4] that the last of the five cysteines that are conserved in the sequence of E1 from various species is the one that binds ubiquitin. We have developed two patterns specific for E1, the first pattern contains the second of the five conserved cysteines while the second pattern includes the active site cysteine.

Last update:

December 2004 / Patterns and text revised.


Technical section

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

UBIQUITIN_ACTIVAT_1, PS00536; Ubiquitin-activating enzyme signature 1  (PATTERN)

UBIQUITIN_ACTIVAT_2, PS00865; Ubiquitin-activating enzyme active site  (PATTERN)


1AuthorsJentsch S. Seufert W. Hauser H.-P.
TitleGenetic analysis of the ubiquitin system.
SourceBiochim. Biophys. Acta 1089:127-139(1991).
PubMed ID1647207

2AuthorsHershko A.
TitleThe ubiquitin pathway for protein degradation.
SourceTrends Biochem. Sci. 16:265-268(1991).
PubMed ID1656558

3AuthorsDohmen R.J. Stappen R. McGrath J.P. Forrova H. Kolarov J. Goffeau A. Varshavsky A.
TitleAn essential yeast gene encoding a homolog of ubiquitin-activating enzyme.
SourceJ. Biol. Chem. 270:18099-18109(1995).
PubMed ID7629121

4AuthorsHatfield P.M. Vierstra R.D.
TitleMultiple forms of ubiquitin-activating enzyme E1 from wheat. Identification of an essential cysteine by in vitro mutagenesis.
SourceJ. Biol. Chem. 267:14799-14803(1992).
PubMed ID1634524

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