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ASB proteins interact with Cullin5 and Rbx2 to form E3 ubiquitin ligase complexes
Author(s) -
Kohroki Junya,
Nishiyama Takehiro,
Nakamura Takaaki,
Masuho Yasuhiko
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.11.016
Subject(s) - ubiquitin ligase , cullin , ankyrin repeat , biology , ubiquitin , dna ligase , microbiology and biotechnology , biochemistry , enzyme , gene
The ankyrin repeat and SOCS box (ASB) family is composed of 18 proteins from ASB1 to ASB18 and belongs to the suppressor of cytokine signaling (SOCS) box protein superfamily. ASB2 was recently shown to interact with a certain Cul–Rbx module to form an E3 ubiquitin (Ub) ligase complex, but the functional composition of the ASB‐containing E3 Ub ligase complexes remains to be characterized. Here, we show that ASB proteins interact with Cul5–Rbx2 but neither Cul2 nor Rbx1 in cells. Mutational analysis revealed that the highly conserved amino acid sequences of the BC box and Cul5 box in the SOCS box of ASB proteins were essential for the interaction with Cul5–Rbx2. Although ASB proteins show slight divergences from the consensus sequences of the BC box and Cul5 box, all five tested ASB proteins bound to Cul5–Rbx2. Furthermore, all three tested ASB complexes containing Cul5–Rbx2 were found to have E3 Ub ligase activity. These findings suggest that the ASB family proteins interact with Cul5–Rbx2 to form E3 Ub ligases and play significant roles via a ubiquitination‐mediated pathway.