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Human δ opioid receptor biogenesis is regulated via interactions with SERCA2b and calnexin
Author(s) -
Tuusa Jussi T.,
Leskelä Tarja T.,
PetäjäRepo Ulla E.
Publication year - 2010
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/j.1742-4658.2010.07699.x
Subject(s) - calnexin , endoplasmic reticulum , microbiology and biotechnology , biogenesis , serca , chaperone (clinical) , biology , receptor , transport protein , er retention , biochemistry , calreticulin , atpase , mutant , enzyme , gene , medicine , pathology
Sarco(endo)plasmic reticulum calcium ATPase (SERCA)2b maintains the cellular Ca 2+ homeostasis by transferring Ca 2+ from the cytosol to the lumen of the endoplasmic reticulum (ER). Recently, SERCA2b has also been shown to be involved in the biosynthesis of secreted and membrane proteins via direct protein–protein interactions, involving components of the ER folding and quality‐control machinery, as well as newly synthesized G protein‐coupled receptors. Here we demonstrate that the human delta opioid receptor (hδOR) exists in a ternary complex with SERCA2b and the ER molecular chaperone calnexin. The interaction between SERCA2b and hδOR in vivo did not require calnexin as it was independent of the C‐terminal calnexin‐interacting domain of SERCA2b. However, the receptor was able to mediate co‐immunoprecipitation of calnexin with the C‐terminally truncated SERCA2b. The association of SERCA2b with hδOR was regulated in vitro by Ca 2+ and ATP in a manner that was opposite to the calnexin–hδOR interaction. Importantly, co‐expression of the catalytically inactive SERCA2b(D351A) or calnexin binding‐compromised SERCA2bΔC mutants with the receptor decreased the expression of mature receptors in a manner that did not directly relate to changes in the ER Ca 2+ concentration. We conclude that dynamic interactions among SERCA2b, calnexin and the hδOR precursor orchestrate receptor biogenesis and are regulated by Ca 2+ and ATP. We further hypothesize that the primary role of SERCA2b in this process is to act as a Ca 2+ sensor in the vicinity of active translocons, integrating protein folding with local fluctuations of ER Ca 2+ levels. Structured digital abstract• MINT‐7889371 : hδORΔC (uniprotkb: P41143 ) physically interacts ( MI:0915 ) with SERCA2b (uniprotkb: P16615 ) by anti tag coimmunoprecipitation ( MI:0007 ) • MINT‐7889483 : hδOR (uniprotkb: P41143 ) physically interacts ( MI:0914 ) with Calnexin (uniprotkb: P27824 ) and SERCA2b (uniprotkb: P16615 ) by anti tag coimmunoprecipitation ( MI:0007 ) • MINT‐7889460 : SERCA2b (uniprotkb: P11607 ) physically interacts ( MI:0914 ) with hδOR (uniprotkb: P41143 ) and Calnexin (uniprotkb: P27824 ) by anti tag coimmunoprecipitation ( MI:0007 ) • MINT‐7889389 : SERCA2b (uniprotkb: P11607 ) physically interacts ( MI:0915 ) with hδOR (uniprotkb: P41143 ) by anti tag coimmunoprecipitation ( MI:0007 ) • MINT‐7889430 : SERCA2b (uniprotkb: P11607 ) physically interacts ( MI:0915 ) with Calnexin (uniprotkb: P27824 ) by anti tag coimmunoprecipitation ( MI:0007 ) • MINT‐7889342 : SERCA2b (uniprotkb: P16615 ) physically interacts ( MI:0914 ) with Calnexin (uniprotkb: P27824 ) and hΔOR (uniprotkb: P41143 ) by anti bait coimmunoprecipitation ( MI:0006 ) • MINT‐7889449 : hδOR (uniprotkb: P41143 ) physically interacts ( MI:0915 ) with Calnexin (uniprotkb: P27824 ) by anti tag coimmunoprecipitation ( MI:0007 )