CSN-subunit Interactions With Other Proteins

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 Also the HIV-1 Tat protein interacts with CSN 3 (our unpublished data). 

CSN4 is a poorly studied subunit of the CSN. Only one interactor of CSN4 has been identified, the ubiquitin-conjugating enzyme COPIO [34]. 

The interaction of CSN5 to the member of the IkB multigene family Bcl3, the progesterone receptor PR, and the steroid receptor co-activator SRC-1, leads to stabilization of Bcl3-p50 and PR-SRC-1 complexes and enhances transcriptional activity [42, 43]. Whereas AP-1 activity is stimulated by interaction of CSN5 with the integrin adhesion receptor LFA-1 [44], the opposite effect was reported in the 

Little is known of GSN8 interactions. CSN8 like CSN3 and CSN4 binds to GOPIO [34]. 

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