Helix 8 of leukotriene B4 type-2 receptor is required for the folding to pass the quality control in the endoplasmic reticulum.
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.
Yasuda
Daisuke
D
Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Okuno
Toshiaki
T
Yokomizo
Takehiko
T
Hori
Tetsuya
T
Hirota
Nobuaki
N
Hashidate
Tomomi
T
Miyano
Masashi
M
Shimizu
Takao
T
Nakamura
Motonao
M
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
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