Protein disulfide isomerase A1 (PDIA1)

Protein disulfide isomerase A1 (PDIA1) is a 57 kDa endoplasmic reticulum-localized enzyme and molecular chaperone that catalyzes the formation, breakage, and rearrangement of disulfide bonds between cysteine residues in proteins. PDIA1 is organized into four globular domains (a, b, b′, a′) plus a C-terminal extension with a KDEL ER-retention sequence. The a and a′ domains contain redox-catalytic CGHC active-site motifs and function independently to perform oxidation, reduction, and isomerization reactions. The b and b′ domains are non-catalytic and primarily involved in substrate spacing and recruitment, with b′ containing a large hydrophobic cavity for binding unfolded protein substrates. PDIA1 accounts for approximately 0.8% of total cellular protein and functions as a critical folding catalyst for secretory pathway proteins. Beyond its role in protein folding, PDIA1 serves as a cofactor for transcription factors including estrogen receptor α, NF-κB, and NRF2, and regulates p53 protein stability. The enzyme undergoes extensive post-translational modifications including phosphorylation, acetylation, ubiquitylation, glycosylation, methylation, and succinylation. PDIA1 exhibits complex roles in cancer, with context-dependent tumor-suppressing or tumor-promoting effects influenced by estrogen receptor status, oxidative stress conditions, and subcellular localization. It has been implicated in cancer metastasis through regulation of the HIF-1α pathway and induction of matrix metalloproteinase secretion.

Other names

PDIP4HB (prolyl 4-hydroxylase β)protein disulfide-isomerase

Catalyzes formation, breakage and isomerization of disulfide bonds, Acts as oxidoreductase and isomerase, Functions as reductase at cell surface, Modulates transcription factor activity (estrogen receptor α, NF-κB, NRF2, p53), Regulates protein stability