Fig. 1

P4HB gene and protein organization. (A). Gene structure of human P4HB gene and predicted splice variants. Exons are represented by boxes; 5′ or 3′ untranslated regions (UTR) are also depicted. ATG indicates the start codon and STOP depicts the stop codon. The underline in P4HB-23 indicates the translated regions. The coding sequence of P4HB-027 includes the 3′ UTR, which does not contain a stop codon. (B). PDIA1 protein domain organization and predicted structure of alternatively processed isoforms. PDIA1 protein is composed of five domains: a, b, b’, a’ and c. The a and a catalytic domains contain the thioredoxin redox-active CGHC motifs (white boxes), while the b and b’ domains (gray boxes) are noncatalytic, structured as thioredoxin folds enriched in hydrophobic residues involved in substrate binding and chaperone activity. An unstructured x-linker stretch is located between b’ and a’ domains and confers flexibility to PDI. The C-terminal c- domain contains the KDEL sequence, an ER retrieval signal