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CKIP‐1 couples Smurf1 ubiquitin ligase with Rpt6 subunit of proteasome to promote substrate degradation
Author(s) -
Wang Yifang,
Nie Jing,
Wang Yiwu,
Zhang Luo,
Lu Kefeng,
Xing Guichun,
Xie Ping,
He Fuchu,
Zhang Lingqiang
Publication year - 2012
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/embor.2012.144
Subject(s) - ubiquitin ligase , proteasome , ubiquitin , dna ligase , microbiology and biotechnology , ubiquitin protein ligases , signal transducing adaptor protein , protein subunit , biology , aaa proteins , activator (genetics) , biochemistry , atpase , chemistry , enzyme , signal transduction , gene
CKIP‐1 is an activator of the Smurf1 ubiquitin ligase acting to promote the ubiquitylation of Smad5 and MEKK2. The mechanisms involved in the recognition and degradation of these substrates by the proteasome remain unclear. Here, we show that CKIP‐1, through its leucine zipper, interacts directly with the Rpt6 ATPase of the 19S regulatory particle of the proteasome. CKIP‐1 mediates the Smurf1–Rpt6 interaction and delivers the ubiquitylated substrates to the proteasome. Depletion of CKIP‐1 reduces the degradation of Smurf1 and its substrates by Rpt6. These findings reveal an unexpected adaptor role of CKIP‐1 in coupling the ubiquitin ligase and the proteasome.