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. Author manuscript; available in PMC: 2009 Sep 29.
Published in final edited form as: Traffic. 2008 Feb 24;9(6):861–870. doi: 10.1111/j.1600-0854.2008.00729.x

Table 1.

Selective components required for ERAD in yeasta

Cytosol- and membrance-associated Merribrane-associated ER lumen- and membrane-associated
ERAD-C Degradation 26S proteasome E3 Doa10
Retrotranslocation Cdc48–Ufd1–Npl4–Ubx2 E2 Ubc6 and Ubc7–Cue1
Chaperones Ssa1, Ydj1 and HIj1
ERAD-M Degradation 26S proteasome E3 Hrd1–Hrd3
Retrotranslocation Cdc48–Ufd1–Npl4–Ubx2 E2 Ubc7–Cue1
ERAD-L Degradation 26S proteasome E3 Hrd1–Hrd3 Putative lectins Yos9 and Htm1/Mnl1
Retrotranslocation Cdc48–Ufd1–Npl4–Ubx2 E2 Ubc7–Cue1 Chaperones BiP (Kar2), Scj1, Jem1 and PDI
Putative retrotranslocon components Der1, Sec61, Ssh1 and Usa1
Other components Polyubiquitination Ufd2
Deubiquitination Rpn11 and Otu1
Escort Rad23–Dsk2
Deglycosylation Png1
a

Components involved in the ERAD-C, -M or -L pathways as listed by their locations. Note that the functions of Ufd2 and Rad23-Dsk2 have not been well characterized for multiple ERAD substrates, and the direct involvement of Rpn11, Otu1 and Png1 during ERAD is still being elucidated. Ubx2 and Cue1 are membrane proteins that recruit the Cdc48 complex and Ubc7 to the ER membrane, respectively. Hrd3 is a membrane protein that stabilizes Hrd1 and recognizes lumenal substrates through its lumenal domain. Usa1 is also a membrane protein that appears to help link the Hrd1 E3 ligase complex and Der1 and is a specific component of the ERAD-L pathway (52).