Serves as a co-chaperone for HSPA5. Binds directly to both unfolded proteins that are substrates for ERAD and nascent unfolded peptide chains, but dissociates from the HSPA5-unfolded protein complex before folding is completed. May help recruiting HSPA5 and other chaperones to the substrate. Stimulates HSPA5 ATPase activity.
Contains 1 J domain.
Contains high-mannose Endo H-sensitive carbohydrates. Cys-169, Cys-171, Cys-193 and Cys-196 form intramolecular disulfide bonds. The preferential partner for each Cys is not known. Thr-188 was reported (PubMed:17525332) to be phosphorylated upon DNA damage by ATM or ATR; however as this position has been shown to be in the ER lumen, the in vivo relevance is not proven.
Endoplasmic reticulum lumen. Associated with the ER membrane in a C-terminally epitope-tagged construct.