Cue1p (coupling of ubiquitin conjugation to ER degradation protein 1) is an integral component of yeast endoplasmic reticulum (ER)-associated degradation (ERAD) ubiquitin ligase (E3) complexes. It tethers the ERAD ubiquitin-conjugating enzyme (E2), Ubc7p, to the ER and prevents its degradation, and also activates Ubc7p. This domain represents the Ubc7p-binding region (U7BR) of Cue1p with Ubc7p. The U7BR is as E2-binding domain that includes three alpha-helices that interact extensively with the 'backside' of Ubc7p. U7BR stimulates both RING-independent and RING-dependent ubiquitin transfer from Ubc7p. Moreover, the U7BR enhances ubiquitin-activating enzyme (E1)-mediated charging of Ubc7p with ubiquitin [1].

1: A structurally unique E2-binding domain activates ubiquitination by the ERAD E2, Ubc7p, through multiple mechanisms. Metzger MB, Liang YH, Das R, Mariano J, Li S, Li J, Kostova Z, Byrd RA, Ji X, Weissman AM; Mol Cell. 2013;50:516-527. PMID:23665230