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ERp44, a novel endoplasmic reticulum folding assistant of the thioredoxin family
Author(s) -
Anelli Tiziana,
Alessio Massimo,
Mezghrani Alexandre,
Simmen Thomas,
Talamo Fabio,
Bachi Angela,
Sitia Roberto
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/21.4.835
Subject(s) - endoplasmic reticulum , biology , protein folding , thioredoxin , microbiology and biotechnology , folding (dsp implementation) , biochemistry , enzyme , engineering , electrical engineering
In human cells, Ero1‐Lα and ‐Lβ (hEROs) regulate oxidative protein folding by selectively oxidizing protein disulfide isomerase. Specific protein–protein interactions are probably crucial for regulating the formation, isomerization and reduction of disulfide bonds in the endoplasmic reticulum (ER). To identify molecules involved in ER redox control, we searched for proteins interacting with Ero1‐Lα. Here, we characterize a novel ER resident protein (ERp44), which contains a thioredoxin domain with a CRFS motif and is induced during ER stress. ERp44 forms mixed disulfides with both hEROs and cargo folding intermediates. Whilst the interaction with transport‐competent Ig‐K chains is transient, ERp44 binds more stably with J chains, which are retained in the ER and eventually degraded by proteasomes. ERp44 does not bind a short‐lived ribophorin mutant lacking cysteines. Its overexpression alters the equilibrium of the different Ero1‐Lα redox isoforms, suggesting that ERp44 may be involved in the control of oxidative protein folding.