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Not curated in GtoImmuPdb
Target id: 114
Nomenclature: GPR68
Family: Class A Orphans with emerging pharmacology
Annotation status:
Annotated and reviewed, awaiting update
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See the Latest Pairings page for more information.
Gene and Protein Information ![]() |
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class A G protein-coupled receptor | ||||||
Species | TM | AA | Chromosomal Location | Gene Symbol | Gene Name | Reference |
Human | 7 | 365 | 14q32.11 | GPR68 | G protein-coupled receptor 68 | 2,34 |
Mouse | 7 | 365 | 12 E | Gpr68 | G protein-coupled receptor 68 | |
Rat | 7 | 375 | 6q32 | Gpr68 | G protein-coupled receptor 68 |
Previous and Unofficial Names ![]() |
GPR12A | Ovarian cancer G-protein coupled receptor 1 | sphingosylphosphorylcholine receptor | OGR1 |
Database Links ![]() |
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Specialist databases | |
GPCRdb | ogr1_human (Hs), ogr1_mouse (Mm) |
Other databases | |
Alphafold | Q15743 (Hs), Q8BFQ3 (Mm) |
ChEMBL Target | CHEMBL3713916 (Hs), CHEMBL4523380 (Mm) |
Ensembl Gene | ENSG00000119714 (Hs), ENSMUSG00000047415 (Mm), ENSRNOG00000046309 (Rn) |
Entrez Gene | 8111 (Hs), 238377 (Mm), 314386 (Rn) |
Human Protein Atlas | ENSG00000119714 (Hs) |
KEGG Gene | hsa:8111 (Hs), mmu:238377 (Mm), rno:314386 (Rn) |
OMIM | 601404 (Hs) |
Pharos | Q15743 (Hs) |
RefSeq Nucleotide | NM_003485 (Hs), NM_175493 (Mm), NM_001108049 (Rn) |
RefSeq Protein | NP_003476 (Hs), NP_780702 (Mm), NP_001101519 (Rn) |
UniProtKB | Q15743 (Hs), Q8BFQ3 (Mm) |
Wikipedia | GPR68 (Hs) |
Natural/Endogenous Ligands ![]() |
Protons |
Endogenous ligand |
Protons |
Download all structure-activity data for this target as a CSV file
Agonists | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Key to terms and symbols | View all chemical structures | Click column headers to sort | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Agonist Comments | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Gpr68 was previously identified as a receptor for sphingosyl phosphorylcholine (SPC) [35], but the original publication has been retracted [39]. However, GPR4, GPR65, GPR68 and GPR132 are now thought to function as proton-sensing receptors detecting acidic pH [4,28]. SPC was later found to antagonise the proton-induced activation of the GPR68-mediated signalling pathways [21,28]. A family of 3,5-disubstituted isoxazoles (Isx) were identified as agonists of GPR68 [26]. |
Antagonist Comments | ||
It has been reported by Wang et al. that psychosine antagonises pH responses by GPR68 [32]. |
Allosteric Modulators | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Key to terms and symbols | View all chemical structures | Click column headers to sort | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Primary Transduction Mechanisms ![]() |
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Transducer | Effector/Response |
Gi/Go family Gq/G11 family |
Adenylyl cyclase inhibition Phospholipase C stimulation |
References: 17,19,33,36 |
Tissue Distribution ![]() |
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Tissue Distribution Comments | ||||||||
GPR68 was expressed early during mouse osteoclast differentiation in vivo and in vitro [36]. GPR68 was strongly regulated in vivo after 2 days of colony stimulating factor-1 treatment [36]. High levels of GPR68 mRNA were detected by microarray, RT-PCR and immunoblotting when mouse bone marrow mononuclear cells and RAW 264.7 pre-osteoclast-like cells were treated with RANKL to induce osteoclast differentiation [13,36]. |
Expression Datasets ![]() |
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Physiological Functions ![]() |
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Physiological Functions Comments | ||||||||
GPR68 transiently increases intracellular calcium, mediates SPC-induced ERK1/2 activation and inhibits cellular proliferation [3]. GPR68 causes cAMP accumulation and inositol phosphate production upon stimulation by extracellular acidification [21]. |
Physiological Consequences of Altering Gene Expression ![]() |
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Physiological Consequences of Altering Gene Expression Comments | ||||||||||
Knockout of GPR68 in mouse macrophages did not affect the acidic pH-induced inhibitory action on cytokine production [20]. |
Phenotypes, Alleles and Disease Models ![]() |
Mouse data from MGI | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Gene Expression and Pathophysiology Comments | |
GPR68 expression was shown to be fivefold lower in metastatic prostate cancers than primary prostate cancers [15]. Gene expression of GPR68 is changed in ASIC3 knockout mice [8]. GPR68 has been reported as a novel metastasis suppressor gene for prostate cancer [17]. |
Biologically Significant Variants ![]() |
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General Comments |
GPR68 is fully activated at pH 6.8, but almost silent at pH 7.8 [18]. Several His residues that reside in the extracellular domain of GPR68 are shown to be responsible for the proton binding, pH-sensing activity of GPR68 [18]. GPR68 forms very weak homodimers and relatively weak heterodimers with other receptors (LPA and GPR4) [38]. GPR68 is coupled to IP3-mediated Cai signalling in osteoblasts [14]. |
1. Afrasiabi E, Blom T, Ekokoski E, Tuominen RK, Törnquist K. (2006) Sphingosylphosphorylcholine enhances calcium entry in thyroid FRO cells by a mechanism dependent on protein kinase C. Cell Signal, 18 (10): 1671-8. [PMID:16490345]
2. An S, Tsai C, Goetzl EJ. (1995) Cloning, sequencing and tissue distribution of two related G protein-coupled receptor candidates expressed prominently in human lung tissue. FEBS Lett, 375 (1-2): 121-4. [PMID:7498459]
3. Bektas M, Barak LS, Jolly PS, Liu H, Lynch KR, Lacana E, Suhr KB, Milstien S, Spiegel S. (2003) The G protein-coupled receptor GPR4 suppresses ERK activation in a ligand-independent manner. Biochemistry, 42 (42): 12181-91. [PMID:14567679]
4. Davenport AP, Alexander SP, Sharman JL, Pawson AJ, Benson HE, Monaghan AE, Liew WC, Mpamhanga CP, Bonner TI, Neubig RR et al.. (2013) International Union of Basic and Clinical Pharmacology. LXXXVIII. G protein-coupled receptor list: recommendations for new pairings with cognate ligands. Pharmacol Rev, 65 (3): 967-86. [PMID:23686350]
5. Foster SR, Hauser AS, Vedel L, Strachan RT, Huang XP, Gavin AC, Shah SD, Nayak AP, Haugaard-Kedström LM, Penn RB et al.. (2019) Discovery of Human Signaling Systems: Pairing Peptides to G Protein-Coupled Receptors. Cell, 179 (4): 895-908.e21. [PMID:31675498]
6. Frick KK, Bushinsky DA. (2010) Effect of metabolic and respiratory acidosis on intracellular calcium in osteoblasts. Am J Physiol Renal Physiol, 299 (2): F418-25. [PMID:20504884]
7. Frick KK, Krieger NS, Nehrke K, Bushinsky DA. (2009) Metabolic acidosis increases intracellular calcium in bone cells through activation of the proton receptor OGR1. J Bone Miner Res, 24 (2): 305-13. [PMID:18847331]
8. Huang CW, Tzeng JN, Chen YJ, Tsai WF, Chen CC, Sun WH. (2007) Nociceptors of dorsal root ganglion express proton-sensing G-protein-coupled receptors. Mol Cell Neurosci, 36 (2): 195-210. [PMID:17720533]
9. Huang WC, Swietach P, Vaughan-Jones RD, Ansorge O, Glitsch MD. (2008) Extracellular acidification elicits spatially and temporally distinct Ca2+ signals. Curr Biol, 18 (10): 781-5. [PMID:18485712]
10. Huang XP, Karpiak J, Kroeze WK, Zhu H, Chen X, Moy SS, Saddoris KA, Nikolova VD, Farrell MS, Wang S et al.. (2015) Allosteric ligands for the pharmacologically dark receptors GPR68 and GPR65. Nature, 527 (7579): 477-83. [PMID:26550826]
11. Ichimonji I, Tomura H, Mogi C, Sato K, Aoki H, Hisada T, Dobashi K, Ishizuka T, Mori M, Okajima F. (2010) Extracellular acidification stimulates IL-6 production and Ca(2+) mobilization through proton-sensing OGR1 receptors in human airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol, 299 (4): L567-77. [PMID:20656891]
12. Jin Y, Damaj BB, Maghazachi AA. (2005) Human resting CD16-, CD16+ and IL-2-, IL-12-, IL-15- or IFN-alpha-activated natural killer cells differentially respond to sphingosylphosphorylcholine, lysophosphatidylcholine and platelet-activating factor. Eur J Immunol, 35 (9): 2699-708. [PMID:16078278]
13. Komarova SV, Pereverzev A, Shum JW, Sims SM, Dixon SJ. (2005) Convergent signaling by acidosis and receptor activator of NF-kappaB ligand (RANKL) on the calcium/calcineurin/NFAT pathway in osteoclasts. Proc Natl Acad Sci USA, 102 (7): 2643-8. [PMID:15695591]
14. Krieger NS, Bushinsky DA. (2011) Pharmacological inhibition of intracellular calcium release blocks acid-induced bone resorption. Am J Physiol Renal Physiol, 300 (1): F91-7. [PMID:21048027]
15. LaTulippe E, Satagopan J, Smith A, Scher H, Scardino P, Reuter V, Gerald WL. (2002) Comprehensive gene expression analysis of prostate cancer reveals distinct transcriptional programs associated with metastatic disease. Cancer Res, 62 (15): 4499-506. [PMID:12154061]
16. Li H, Wang D, Singh LS, Berk M, Tan H, Zhao Z, Steinmetz R, Kirmani K, Wei G, Xu Y. (2009) Abnormalities in osteoclastogenesis and decreased tumorigenesis in mice deficient for ovarian cancer G protein-coupled receptor 1. PLoS ONE, 4 (5): e5705. [PMID:19479052]
17. Liu JP, Komachi M, Tomura H, Mogi C, Damirin A, Tobo M, Takano M, Nochi H, Tamoto K, Sato K, Okajima F. (2010) Ovarian cancer G protein-coupled receptor 1-dependent and -independent vascular actions to acidic pH in human aortic smooth muscle cells. Am J Physiol Heart Circ Physiol, 299 (3): H731-42. [PMID:20622109]
18. Ludwig MG, Vanek M, Guerini D, Gasser JA, Jones CE, Junker U, Hofstetter H, Wolf RM, Seuwen K. (2003) Proton-sensing G-protein-coupled receptors. Nature, 425 (6953): 93-8. [PMID:12955148]
19. Matsuzaki S, Ishizuka T, Yamada H, Kamide Y, Hisada T, Ichimonji I, Aoki H, Yatomi M, Komachi M, Tsurumaki H et al.. (2011) Extracellular acidification induces connective tissue growth factor production through proton-sensing receptor OGR1 in human airway smooth muscle cells. Biochem Biophys Res Commun, 413 (4): 499-503. [PMID:21907704]
20. Mogi C, Tobo M, Tomura H, Murata N, He XD, Sato K, Kimura T, Ishizuka T, Sasaki T, Sato T, Kihara Y, Ishii S, Harada A, Okajima F. (2009) Involvement of proton-sensing TDAG8 in extracellular acidification-induced inhibition of proinflammatory cytokine production in peritoneal macrophages. J Immunol, 182 (5): 3243-51. [PMID:19234222]
21. Mogi C, Tomura H, Tobo M, Wang JQ, Damirin A, Kon J, Komachi M, Hashimoto K, Sato K, Okajima F. (2005) Sphingosylphosphorylcholine antagonizes proton-sensing ovarian cancer G-protein-coupled receptor 1 (OGR1)-mediated inositol phosphate production and cAMP accumulation. J Pharmacol Sci, 99 (2): 160-7. [PMID:16210776]
22. Mohebbi N, Benabbas C, Vidal S, Daryadel A, Bourgeois S, Velic A, Ludwig MG, Seuwen K, Wagner CA. (2012) The proton-activated G protein coupled receptor OGR1 acutely regulates the activity of epithelial proton transport proteins. Cell Physiol Biochem, 29 (3-4): 313-24. [PMID:22508039]
23. Murata N, Mogi C, Tobo M, Nakakura T, Sato K, Tomura H, Okajima F. (2009) Inhibition of superoxide anion production by extracellular acidification in neutrophils. Cell Immunol, 259 (1): 21-6. [PMID:19539899]
24. Pereverzev A, Komarova SV, Korcok J, Armstrong S, Tremblay GB, Dixon SJ, Sims SM. (2008) Extracellular acidification enhances osteoclast survival through an NFAT-independent, protein kinase C-dependent pathway. Bone, 42 (1): 150-61. [PMID:17964236]
25. Ren J, Zhang L. (2011) Effects of ovarian cancer G protein coupled receptor 1 on the proliferation, migration, and adhesion of human ovarian cancer cells. Chin Med J, 124 (9): 1327-32. [PMID:21740742]
26. Russell JL, Goetsch SC, Aguilar HR, Coe H, Luo X, Liu N, van Rooij E, Frantz DE, Schneider JW. (2012) Regulated expression of pH sensing G Protein-coupled receptor-68 identified through chemical biology defines a new drug target for ischemic heart disease. ACS Chem Biol, 7 (6): 1077-83. [PMID:22462679]
27. Saxena H, Deshpande DA, Tiegs BC, Yan H, Battafarano RJ, Burrows WM, Damera G, Panettieri RA, Dubose TD, An SS et al.. (2012) The GPCR OGR1 (GPR68) mediates diverse signalling and contraction of airway smooth muscle in response to small reductions in extracellular pH. Br J Pharmacol, 166 (3): 981-90. [PMID:22145625]
28. Seuwen K, Ludwig MG, Wolf RM. (2006) Receptors for protons or lipid messengers or both?. J Recept Signal Transduct Res, 26 (5-6): 599-610. [PMID:17118800]
29. Tomura H, Mogi C, Sato K, Okajima F. (2005) Proton-sensing and lysolipid-sensitive G-protein-coupled receptors: a novel type of multi-functional receptors. Cell Signal, 17 (12): 1466-76. [PMID:16014326]
30. Tomura H, Wang JQ, Komachi M, Damirin A, Mogi C, Tobo M, Kon J, Misawa N, Sato K, Okajima F. (2005) Prostaglandin I(2) production and cAMP accumulation in response to acidic extracellular pH through OGR1 in human aortic smooth muscle cells. J Biol Chem, 280 (41): 34458-64. [PMID:16087674]
31. Tomura H, Wang JQ, Liu JP, Komachi M, Damirin A, Mogi C, Tobo M, Nochi H, Tamoto K, Im DS, Sato K, Okajima F. (2008) Cyclooxygenase-2 expression and prostaglandin E2 production in response to acidic pH through OGR1 in a human osteoblastic cell line. J Bone Miner Res, 23 (7): 1129-39. [PMID:18302504]
32. Wang JQ, Kon J, Mogi C, Tobo M, Damirin A, Sato K, Komachi M, Malchinkhuu E, Murata N, Kimura T, Kuwabara A, Wakamatsu K, Koizumi H, Uede T, Tsujimoto G, Kurose H, Sato T, Harada A, Misawa N, Tomura H, Okajima F. (2004) TDAG8 is a proton-sensing and psychosine-sensitive G-protein-coupled receptor. J Biol Chem, 279 (44): 45626-33. [PMID:15326175]
33. Xu Y. (2002) Sphingosylphosphorylcholine and lysophosphatidylcholine: G protein-coupled receptors and receptor-mediated signal transduction. Biochim Biophys Acta, 1582 (1-3): 81-8. [PMID:12069813]
34. Xu Y, Casey G. (1996) Identification of human OGR1, a novel G protein-coupled receptor that maps to chromosome 14. Genomics, 35 (2): 397-402. [PMID:8661159]
35. Xu Y, Zhu K, Hong G, Wu W, Baudhuin LM, Xiao Y, Damron DS. (2000) Sphingosylphosphorylcholine is a ligand for ovarian cancer G-protein-coupled receptor 1. Nat Cell Biol, 2 (5): 261-7 RETRACTED. [PMID:10806476]
36. Yang M, Mailhot G, Birnbaum MJ, MacKay CA, Mason-Savas A, Odgren PR. (2006) Expression of and role for ovarian cancer G-protein-coupled receptor 1 (OGR1) during osteoclastogenesis. J Biol Chem, 281 (33): 23598-605. [PMID:16787916]
37. Yu X, Huang XP, Kenakin TP, Slocum ST, Chen X, Martini ML, Liu J, Jin J. (2019) Design, Synthesis, and Characterization of Ogerin-Based Positive Allosteric Modulators for G Protein-Coupled Receptor 68 (GPR68). J Med Chem, 62 (16): 7557-7574. [PMID:31298539]
38. Zaslavsky A, Singh LS, Tan H, Ding H, Liang Z, Xu Y. (2006) Homo- and hetero-dimerization of LPA/S1P receptors, OGR1 and GPR4. Biochim Biophys Acta, 1761 (10): 1200-12. [PMID:17023202]
39. (2006) Retraction. Sphingosylphosphorylcholine is a ligand for ovarian cancer G-protein-coupled receptor 1. Nat Cell Biol, 8 (3): 299. [PMID:16508674]