Ubiquitin ligase

Adaptor Proteins. Figure 1 Adaptor protein domains. A scheme of the domain structures of some well-characterized adaptor proteins is shown. Descriptions of domain characteristics are in main text except C2, binds to phospholipids GTPase activating protein (GAP) domain, inactivates small GTPases such as Ras Hect domain, enzymatic domain of ubiquitin ligases and GUK domain, guanylate kinase domain. For clarity, not all domains contained within these proteins are shown. 

WW domains (named after the one letter abbreviation for the amino acid tryptophan) are small regions of around 30 residues, which, like SH3 domains, bind to polyproline sequences. These sequences often contain the consensus sequence PPXY or PPLP. Examples of proteins that contain WW domains include Nedd4 E3 ubiquitin ligase (Fig. 1) and IQGAP1. 

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Proteins with destabilizing N-terminal residues such as arginine and leucine are recognized by a RING-type ubiquitin ligase (termed N-recognin or E3-a) that, together with a specific ubiquitin c, mediates poly-ubiquitylation. 

Parkin is a ubiquitin ligase encoded by a gene affected in autosomal recessive juvenile parkinsonism (AR-JP). This gene is located on chromosome 6 and encodes a protein of 465 amino acid residues with moderate similarity to ubiquitin at the amino terminus and a RING-finger motif at the carboxy terminus. 

The SCF, a ubiquitin ligase complex, consists of the piimaiy subunits Skpl, Cullin and Rbx/Rocl. While the Rbx/Cul components form the E3 ligase catalytic core... 

Ubiquitin tags proteins for protein degradation. The ubiquitination requires three different enzymatic activities, a ubiquitin-activating enzyme (El), a ubiquitin-conjugating enzyme (E2 or Ubc) and a ubiquitin ligase (E3). The action of all three enzymes leads to the establishment of a poly-ubiquitin chain on target proteins which are then recognized and proteolyzed by the 26S proteasome. 

Gack MU, Shin YC, Joo CH, Urano T, Liang C, Sun L, Takeuchi O, Akira S, ChenZ, Inoue S, Jung JU (2007) TRIM25 RING-flnger E3 ubiquitin ligase is essential for RIG-I-mediated antiviral activity. Nature 446 916-920... 

Marchese A, Raiborg C, Santini F, Keen JH, Stenmark H, Benovic JL. The E3 ubiquitin ligase AIP4 mediates ubiquitination and sorting of the G protein-coupled receptor CXCR4. Dev Cell 2003 5(5) 709-722. 

Mailer That is a question I have been wanting to address. The apoptosis response can be driven wholly by a maternal programme that doesn t require transcription. If it is p53-dependent, it would be a non-transcriptional effect of p53. We haven t been able to completely get rid of p53. The most direct approach we have tried is to inject the papilloma virus E6 protein into embryos. This is an E3 ubiquitin ligase that degrades p53. There is something like lOng of p53 in every oocyte, so we can only get rid of half of this. Thus we haven t been able to answer the question of whether this response is p53 dependent or not. 

Nasmyth Have you tried adding Rsk to the APC ubiquitin ligase assays directly ... 

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