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A role for calnexin (IP90) in the assembly of class II MHC molecules.
Author(s) -
Anderson K.S.,
Cresswell P.
Publication year - 1994
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 - 10.1002/j.1460-2075.1994.tb06306.x
Subject(s) - calnexin , haven , major histocompatibility complex , biology , antigen , immunology , endoplasmic reticulum , genetics , combinatorics , mathematics , calreticulin
Major histocompatibility complex (MHC) class II antigens consist of alpha and beta chains that associate intracellularly with the invariant (I) chain. The HLA‐DR alpha beta I complex assembles in the endoplasmic reticulum (ER) into a nonameric structure via progressive addition of three alpha beta dimers to a core invariant chain trimer. We have examined intracellular association of alpha beta I complexes with the resident ER protein calnexin. Calnexin associates rapidly (within 3 min) with newly synthesized alpha, beta and I chains, and remains associated with the assembling alpha beta I complex until the final alpha beta dimer is added, forming the complete nonamer. Dissociation of calnexin parallels egress of alpha beta I from the ER. These results suggest that calnexin retains and stabilizes both free class II subunits and partially assembled class II‐I chain complexes until assembly of the nonamer is complete.