Enzymes with Additional Ubiquitin-binding Sites

Enzymes with Additional Ubiquitin-binding Sites 

A related adapter family combines the UBA domain with a UBX domain, which is much more distantly related to ubiquitin than the true UbL domains [44, 45]. In these proteins, the UBA domain is frequently found at the N-terminus while the UBX domain forms the C-terminus of the protein an example is the yeast Shpl protein and its mammalian homolog p47. So far, there is limited data on the function of this protein family though they appear to shuttle ubiquitinated proteins to the Cdc48/p97 complex instead of to the proteasome [47, 106]. 

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Enzymes with Additional Ubiquitin-binding Sites... 

The CSN3 subunit interacts with IKKy, a component of the IsrB-kinase complex controlling NF-kB activity [32]. Additionally, it is the binding site for the CSN-associated kinases CK2 and PKD [31]. The subunit of the translation-initiation factor 3 complex, Int6/eIF3e, and the ubiquitin-conjugating enzyme variant, COPIO, have been identified as other cellular interactors [33, 34]. Also the HIV-1 Tat protein interacts with CSN 3 (our unpublished data). 

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