Table 2.

Topology and function of ERdj proteins.

	Topology	Function
ERdj1	Integral membrane protein with a luminal J-domain and cytosolic C-terminus	Binding to the ribosome (60 S subunit) near the tunnel exit In the absence of BiP: translational block In the presence of BiP: translational release
ERdj2	Integral membrane protein with the luminal J-domain and a cytosolic C-domain	At the cytosolic site: association with the translocon proteins Sec61 α, β, γ, and Sec62 Transport of proteins across the ER membrane to control the protein load in the ER
ERdj3	Within the ER lumen: Major pool: part of large protein complexes Minor pool: as free protein pool --------------------------------------------- Integral membrane protein: minor pool In the absence of accessory proteins: head-on insertion (cytosolic orientation) In the presence of accessory proteins: loop insertion (luminal orientation)	Interaction with the Sec61 translocon Promoting protein degradation via ERAD --------------------------------------------- Putative transcription factor in the nucleus
ERdj4	70–75% of the protein: soluble in the ER lumen --------------------------------------------- 25–30% of the protein: integral membrane protein facing the cytosol	Targeting of proteins to the ERAD pathway Protein folding Induction of apoptosis ---------------------------------------------
ERdj5	Luminal localization	Acceleration of the ERAD pathway Protein folding Apoptosis
ERdj6	Major pool: luminal localization --------------------------------------------- Minor pool: integral membrane protein facing the cytosol	Protein maturation and post-ER transport of target proteins --------------------------------------------- Inhibition of protein synthesis by - Direct binding to the kinase domains of PKR, PERK, and GCN2 kinases - Very efficient control of eIF2a phosphorylation
ERdj7	ER-localization