DnaJ homolog subfamily B member 9 (Endoplasmic reticulum DNA J domain-containing protein 4) (ER-resident protein ERdj4) (ERdj4) (Microvascular endothelial differentiation gene 1 protein) (Mdg-1)
1_MATPQ 6_ SIFIF 11_ AICIL 16_ MITEL 21_ ILASK 26_ SYYDI 31_ LGVPK 36_ SASER 41_ QIKKA 46_ FHKLA 51_ MKYHP 56_ DKNKS 61_ PDAEA 66_ KFREI 71_ AEAYE 76_ TLSDA 81_ NRRKE 86_ YDTLG 91_ HSAFT 96_ SGKGQ 101_ RGSGS 106_ SFEQS 111_ FNFNF 116_ DDLFK 121_ DFGFF 126_ GQNQN 131_ TGSKK 136_ RFENH 141_ FQTRQ 146_ DGGSS 151_ RQRHH 156_ FQEFS 161_ FGGGL 166_ FDDMF 171_ EDMEK 176_ MFSFS 181_ GFDST 186_ NQHTV 191_ QTENR 196_ FHGSS 201_ KHCRT 206_ VTQRR 211_ GNMVT 216_TYTDC
1: Co-chaperone for Hsp70 protein HSPA5/BiP that acts as a key repressor of the ERN1/IRE1-mediated unfolded protein response (UPR) (By similarity). J domain-containing co-chaperones stimulate the ATPase activity of Hsp70 proteins and are required for efficient substrate recognition by Hsp70 proteins (PubMed:18400946). In the unstressed endoplasmic reticulum, interacts with the luminal region of ERN1/IRE1 and selectively recruits HSPA5/BiP: HSPA5/BiP disrupts the dimerization of the active ERN1/IRE1 luminal region, thereby inactivating ERN1/IRE1 (By similarity). Also involved in endoplasmic reticulum-associated degradation (ERAD) of misfolded proteins. Required for survival of B-cell progenitors and normal antibody production (By similarity)