CUE domain found in yeast ubiquitin-binding protein CUE1 (Cue1p), CUE4 (Cue4p) and similar proteins
Cue1p, also called coupling of ubiquitin conjugation to ER degradation protein 1 or kinetochore-defect suppressor 4, is encoded by the open reading frame (ORF) YMR264W in yeast. It is an N-terminally membrane-anchored endoplasmic reticulum (ER) protein essential for the activity of the two major yeast RING finger ubiquitin ligases (E3s) implicated in ER-associated degradation (ERAD). It interacts with the ERAD ubiquitin-conjugating enzyme (E2) Ubc7p in vivo, stimulates Ubc7p E2 activity, and further activates ER-associated protein degradation. Cue1p contains a CUE domain which binds ubiquitin much more weakly than those of other CUE domain containing proteins. It also has an Ubc7p binding-domain at the C-terminal region which is required for Ubc7p-dependent ubiquitylation and for degradation of substrates in the ER. This family also includes Cue4p, also called coupling of ubiquitin conjugation to ER degradation protein 4. It is encoded by the open reading frame (ORF) YML101C in yeast. Cue4p contains a CUE domain which shows high level of similarity with that of Cue1p.
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