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N– linked glycosylation modulates dimerization of protein disulfide isomerase family A member 2 ( PDIA 2)
Author(s) -
Walker Adam K.,
Soo Kai Ying,
Levina Vita,
Talbo Gert H.,
Atkin Julie D.
Publication year - 2013
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.12063
Subject(s) - protein disulfide isomerase , endoplasmic reticulum , glycosylation , calnexin , endoplasmic reticulum associated protein degradation , protein folding , n linked glycosylation , biochemistry , golgi apparatus , chemistry , mutant , foldase , unfolded protein response , microbiology and biotechnology , biology , glycoprotein , glycan , calreticulin , gene , escherichia coli , groel
Protein disulfide isomerase ( PDI ) family members are important enzymes for the correct folding and maturation of proteins that transit or reside in the endoplasmic reticulum ( ER ). The human PDI family comprises at least 19 members that differ in cell type expression, substrate specificity and post‐translational modifications. PDI family A member 2 ( PDIA 2, previously known as PDI p) has a similar domain structure to prototypical PDI (also known as PDIA 1), but the function and post‐translational modifications of PDIA 2 remain poorly understood. Unlike most PDI family members, PDIA 2 contains three predicted N ‐linked glycosylation sites. By site‐directed mutagenesis and enzymatic deglycosylation, we show here that all three Asn residues within the potential N ‐linked glycosylation sites of human PDIA 2 (N127, N284 and N516) are glycosylated in human cells. Furthermore, mutation of N284 to glycosylation‐null Gln increases formation of a highly stable disulfide‐bonded PDIA 2 dimer. Nevertheless, in H e L a cells, both wild‐type and N 127/284/516 Q mutant PDIA 2 proteins localize to the ER , but not the ER –Golgi intermediate compartment, suggesting that glycosylation is important for PDIA 2 protein–protein interactions but not subcellular localization. Finally, we identified human major histocompatibility complex class 1 antigens ( HLA ‐ A , B , C ) as potential binding partners of PDIA 2, suggesting an involvement for PDIA 2 in antigen presentation in addition to its previously described roles in autoimmunity and Parkinson's disease. These results further characterize this poorly defined member of the PDI family. Structured digital abstract • Calreticulin and PDIA2 colocalize by fluorescence microscopy ( View interaction ) • PDIA2 and PDIA1 colocalize by fluorescence microscopy ( View interaction )