title: Helix 8 of leukotriene B4 type-2 receptor is required for the folding to pass the quality control in the endoplasmic reticulum.
abstract: Many G protein-coupled receptors (GPCRs) possess a putative cytoplasmic helical domain, termed helix 8 (H8), at the proximal region of the C-terminal tail. However, the significance of this domain is not fully understood. Here, we demonstrate the requirement of H8 for the proper folding of GPCRs for passage through the quality control in the endoplasmic reticulum (ER). In the human leukotriene B(4) type-2 receptor (hBLT2), lack of H8 led to an accumulation of the receptor (hBLT2/DeltaH8) in the ER. Similar results were obtained in two representative human GPCRs, dopamine type-1 and lysophosphatidic acid type-2 receptors, which were engineered to lack H8. Treatment with the several ligands, which act as pharmacological chaperones, facilitated the surface expression of hBLT2/DeltaH8. The surface-trafficked hBLT2/DeltaH8 exhibited an agonist-evoked increase in Ca(2+), demonstrating that H8 is not critical for ligand binding and activation of coupled G proteins. Thus, these results suggest that the H8 region of hBLT2 plays an important role in transport-competent receptor folding.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yasuda
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Okuno
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yokomizo
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hori
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Hirota
authors.forename: Tomomi
authors.initials: T
authors.lastname: Hashidate
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyano
authors.forename: Takao
authors.initials: T
authors.lastname: Shimizu
authors.forename: Motonao
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D017510:Protein Folding; D021381:Protein Transport; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D018102:Receptors, Leukotriene B4 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D049368:Receptors, Lysophosphatidic Acid / Q000378:metabolism
chemical_list: D005231:Fatty Acids, Unsaturated; C485878:LTB4R2 protein, human; D017447:Receptors, Dopamine D1; D018102:Receptors, Leukotriene B4; D049368:Receptors, Lysophosphatidic Acid; C008033:12-hydroxy-5,8,10-heptadecatrienoic acid; D002118:Calcium