Extended Data Fig. 5: Structural comparisons and stable interactions of other ER luminal proteins with PDI or the related ERp57 protein.

(a) Overlay of a cartoon model of the MHD of Mnl1 in the Mnl1-Pdi1 structure with the MHD of Mns1 (PDB code: 1DL2). (b) Overlay of Pdi1 in the Mnl1-Pdi1 structure with the reduced state of human PDI (PDB code: 4EKZ). (c) Overlay of the CGHC motifs of the Trx a and Trx a’ domains of Pdi1 and the interacting Mnl1 loop segments. (d) Overlay of the Mnl1-Pdi1 structure with the structure of ERp57 bound to tapasin, a protein involved in peptide loading onto the MHC class I complex (PDB code: 3F8U). The Trx domains of Pdi1 and ERp57 are shown in cyan and grey, respectively. The Mnl1 loop is shown in red. (e) As in (d), but overlay of Mnl1-Pdi1 with the structure of PDI bound to microsomal triglyceride transfer protein (MTP), a protein involved in lipid transfer to apolipoprotein B (PDB code: 6I7S). (f) As in (d), but overlay of Mnl1-Pdi1 with the structure of PDI bound to collagen prolyl 4-hydroxylases (C-P4H), a protein involved in collagen synthesis (PDB code: 7ZSC). (g) Overlay of the Trx a domains of Mnl1-Pdi1 and tapasin-Pdi1 (cyan and blue). The interacting Mnl1 and tapasin loops are shown in red and yellow, respectively. Note that the loops have cysteines that form disulfides with the first cysteine of the CXXC motifs. (h) As in (g), but for the Trx a’ domains of Mnl1-Pdi1 and MTP-Pdi1. The loop of MTP is colored in pink. (i) As in (g), but for the Trx a domains of Mnl1-Pdi1 and C-P4H-Pdi1. The loop of C-P4H is colored in wheat. (j) As in (i), but for the Trx a’ domains.