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Byambaragchaa M, Park H, Kim D, Lee J, Kang M, Min K. The N-Linked Glycosylation Site N191 Is Necessary for PKA Signal Transduction in Eel Follicle-Stimulating Hormone Receptor. Int J Mol Sci 2022; 23:12792. [PMID: 36361582 PMCID: PMC9655291 DOI: 10.3390/ijms232112792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 11/24/2022] Open
Abstract
The follicle-stimulating hormone receptor (FSHR) contains several N-linked glycosylation sites in its extracellular region. We conducted the present study to determine whether conserved glycosylated sites in eel FSHR are necessary for cyclic adenosine monophosphate (cAMP) signal transduction. We used site-directed mutagenesis to induce four mutations (N120Q, N191Q, N272Q, and N288Q) in the N-linked glycosylation sites of eel FSHR. In the eel FSHR wild-type (wt), the cAMP response was gradually increased in a dose-dependent manner (0.01–1500 ng/mL), displaying a high response (approximately 57.5 nM/104 cells) at the Rmax level. Three mutants (N120Q, N272Q, and N288Q) showed a considerably decreased signal transduction as a result of high-ligand treatment, whereas one mutant (N191Q) exhibited a completely impaired signal transduction. The expression level of the N191Q mutant was only 9.2% relative to that of the eel FSHR-wt, indicating a negligible expression level. The expression levels of the N120Q and N272Q mutants were approximately 35.9% and 24% of the FSHG-wt, respectively. The N288Q mutant had an expression level similar to that of the eel FSHR-wt, despite the mostly impaired cAMP responsiveness. The loss of the cell surface agonist-receptor complexes was very rapid in the cells expressing eel FSHR-wt and FSHR-N288Q mutants. Specifically, the N191Q mutant was completely impaired by the loss of cell surface receptors, despite treatment with a high concentration of the agonist. Therefore, we suggest that the N191 site is necessary for cAMP signal transduction. This finding implies that the cAMP response, mediated by G proteins, is directly related to the loss of cell surface receptors as a result of high-agonist treatment.
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Byambaragchaa M, Choi SH, Kim DW, Min KS. Constitutive Activating Eel Luteinizing Hormone Receptors Induce Constitutively Signal Transduction and Inactivating Mutants Impair Biological Activity. Dev Reprod 2021; 25:133-143. [PMID: 34950817 PMCID: PMC8670774 DOI: 10.12717/dr.2021.25.3.133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/19/2021] [Accepted: 08/25/2021] [Indexed: 11/17/2022]
Abstract
In contrast to the human lutropin receptor (hLHR) and rat LHR (rLHR), very few
naturally occurring mutants in other mammalian species have been identified. The
present study aimed to delineate the mechanism of signal transduction by three
constitutively activating mutants (designated M410T, L469R, and D590Y) and two
inactivating mutants (D383N and Y546F) of the eel LHR, known to be naturally
occurring in human LHR transmembrane domains. The mutants were constructed and
measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous
time-resolved fluorescence assays in Chinese hamster ovary (CHO)-K1 cells. The
activating mutant cells expressing eel LHR-M410T, L469R, and D590Y exhibited a
4.0-, 19.1-, and 7.8-fold increase in basal cAMP response without agonist
treatment, respectively. However, inactivating mutant cells expressing D417N and
Y558F did not completely impaired signal transduction. Specifically, signal
transduction in the cells expressing activating mutant L469R was not occurred
with a further ligand stimulation, showing that the maximal response exhibited
approximately 53% of those of wild type receptor. Our results suggested that the
constitutively activating mutants of the eel LHR consistently occurred without
agonist treatment. These results provide important information of LHR function
in fish and regulation with regard to mutations of highly conserved amino acids
in glycoprotein hormone receptors.
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Affiliation(s)
| | - Seung-Hee Choi
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Dong-Wan Kim
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea.,School of Animal Life Convergence Science, Hankyong National University, Ansung 17579, Korea
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Byambaragchaa M, Choi SH, Joo HE, Kim SG, Kim YJ, Park GE, Kang MH, Min KS. Specific Biological Activity of Equine Chorionic Gonadotropin (eCG) Glycosylation Sites in Cells Expressing Equine Luteinizing Hormone/CG (eLH/CG) Receptor. Dev Reprod 2021; 25:199-211. [PMID: 35141446 PMCID: PMC8807129 DOI: 10.12717/dr.2021.25.4.199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/02/2021] [Accepted: 11/23/2021] [Indexed: 11/30/2022]
Abstract
Equine chorionic gonadotropin (eCG), produced by the endometrial cups of the
placenta after the first trimester, is a specific glycoprotein that displays
dual luteinizing hormone (LH)-like and follicle-stimulating hormone (FSH)-like
effects in non-equid species. However, in equidaes, eCG exhibits only LH-like
activity. To identify the specific biological functions of glycosylated sites in
eCG, we constructed the following site mutants of N- and O-linked glycosylation:
eCGβ/αΔ56, substitution of α-subunit56
N-linked glycosylation site; eCGβ-D/α, deletion of the O-linked
glycosylation sites at the β-subunit, and
eCGβ-D/αΔ56, double mutant. We produced recombinant eCG
(rec-eCG) proteins in Chinese hamster ovary suspension (CHO-S) cells. We
examined the biological activity of rec-eCG proteins in CHO-K1 cells expressing
the eLH/CG receptor and found that signal transduction activities of
deglycosylated mutants remarkably decreased. The EC50 levels of
eCGβ/αΔ56, eCGβ-D/α, and
eCGβ-D/αΔ56 mutants decreased by 2.1-, 5.6-, and 3.4-fold,
respectively, compared to that of wild-type eCG. The Rmax values of the mutants
were 56%-80% those of wild-type eCG (141.9 nmol/104 cells). Our
results indicate that the biological activity of eCG is greatly affected by the
removal of N- and O-linked glycosylation sites in cells expressing eLH/CGR.
These results provide important information on rec-eCG in the regulation of
specific glycosylation sites and improve our understanding of the specific
biological activity of rec-eCG glycosylation sites in equidaes.
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Affiliation(s)
| | - Seung-Hee Choi
- Animal Biotechnology, Hankyong National University, Ansung 17579, Korea
| | - Hyo-Eun Joo
- Dept. of Animal Life Science, Hankyong National University, Ansung 17579, Korea
| | - Sang-Gwon Kim
- Dept. of Animal Life Science, Hankyong National University, Ansung 17579, Korea
| | - Yean-Ji Kim
- Dept. of Animal Life Science, Hankyong National University, Ansung 17579, Korea
| | - Gyeong-Eun Park
- Dept. of Animal Life Science, Hankyong National University, Ansung 17579, Korea
| | - Myung-Hwa Kang
- Dept. of Food Science and Nutrition, Hoseo University, Asan 31499, Korea
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea.,Animal Biotechnology, Hankyong National University, Ansung 17579, Korea.,Dept. of Animal Life Science, Hankyong National University, Ansung 17579, Korea
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Byambaragchaa M, Choi SH, Kim DW, Min KS. Cell-Surface Loss of Constitutive Activating and Inactivating Mutants of Eel Luteinizing Hormone Receptors. Dev Reprod 2021; 25:225-234. [PMID: 35141448 PMCID: PMC8807125 DOI: 10.12717/dr.2021.25.4.225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/02/2021] [Accepted: 12/11/2021] [Indexed: 12/14/2022]
Abstract
The present study aimed to investigate the mechanism of cell surface receptor loss by two constitutively activating mutants (designated L469R, and D590Y) and two inactivating mutants (D417N and Y558F) of the luteinizing hormone receptor (LHR) in the Japanese eel Anguilla japonica, known to naturally occur in human LHR transmembrane domains. We investigated cell surface receptor loss using an enzyme-linked immunosorbent assay in HEK 293 cells. The expression level of wild-type eel LHR was considered to be 100%, and the expression levels of L469R and D417N were 97% and 101%, respectively, whereas the expression levels of D590Y and Y558F slightly increased to approximately 110% and 106%, respectively. The constitutively activating mutants L469R and D590Y exhibited a decrease in cell surface loss in a manner similar to that of wild-type eel LHR. The rates of loss of cell surface agonist-receptor complexes were observed to be very rapid (2.6-6.2 min) in both the wild-type eel LHR and activating mutants. However, cell surface receptor loss in the cells expressing inactivating mutants D417N and Y558F was slightly observed in the cells expressing inactivating mutants D417N and Y558F, despite treatment with a high concentration of agonist. These results provide important information on LHR function in fish and the regulation of mutations of highly conserved amino acids in glycoprotein hormone receptors.
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Affiliation(s)
| | - Seung-Hee Choi
- School of Animal Life Convergence Science, Hankyong National University, Ansung 17579, Korea
| | - Dong-Wan Kim
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea.,School of Animal Life Convergence Science, Hankyong National University, Ansung 17579, Korea
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Byambaragchaa M, Seong HK, Choi SH, Kim DJ, Kang MH, Min KS. Constitutively Activating Mutants of Equine LH/CGR Constitutively Induce Signal Transduction and Inactivating Mutations Impair Biological Activity and Cell-Surface Receptor Loss In Vitro. Int J Mol Sci 2021; 22:ijms221910723. [PMID: 34639064 PMCID: PMC8509413 DOI: 10.3390/ijms221910723] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 12/26/2022] Open
Abstract
The signal transduction of the equine lutropin/choriogonadotropin receptor (eLH/CGR) is unclear in naturally occurring activating/inactivating mutants of this receptor, which plays an important role in reproductive physiology. We undertook the present study to determine whether conserved structurally related mutations in eLH/CGR exhibit similar mechanisms of signal transduction. We constructed four constitutively activating mutants (M398T, L457R, D564G, and D578Y) and three inactivating mutants (D405N, R464H, and Y546F); measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary cells; and investigated cell-surface receptor loss using an enzyme-linked immunosorbent assay in human embryonic kidney 293 cells. The eLH/CGR-L457R-, -D564G-, and -D578Y-expressing cells exhibited 16.9-, 16.4-, and 11.2-fold increases in basal cAMP response, respectively. The eLH/CGR-D405N- and R464H-expressing cells presented a completely impaired signal transduction, whereas the Y546F-expressing cells exhibited a small increase in cAMP response. The cell-surface receptor loss was 1.4- to 2.4-fold greater in the activating-mutant-expressing cells than in wild-type eLH/CGR-expressing cells, but was completely impaired in the D405N- and Y546F-expressing cells, despite treatment with a high concentration of agonist. In summary, the state of activation of eLH/CGR influenced agonist-induced cell-surface receptor loss, which was directly related to the signal transduction of constitutively activating mutants.
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Affiliation(s)
- Munkhzaya Byambaragchaa
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
| | - Hoon-Ki Seong
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
| | - Seung-Hee Choi
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea;
| | - Dae-Jung Kim
- Jeju Fisheries Research Institute, National Institute of Fisheries Science (NIFS), Jeju 63610, Korea;
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan 31499, Korea;
| | - Kwan-Sik Min
- Institute of Genetic Engineering, Hankyong National University, Ansung 17579, Korea; (M.B.); (H.-K.S.)
- Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, Korea;
- Correspondence: ; Tel.: +82-31-670-5421; Fax: +82-31-670-5417
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Lee SY, Byambaragchaa M, Choi SH, Kang HJ, Kang MH, Min KS. Roles of N-linked and O-linked glycosylation sites in the activity of equine chorionic gonadotropin in cells expressing rat luteinizing hormone/chorionic gonadotropin receptor and follicle-stimulating hormone receptor. BMC Biotechnol 2021; 21:52. [PMID: 34482828 PMCID: PMC8419929 DOI: 10.1186/s12896-021-00712-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 09/01/2021] [Indexed: 12/04/2022] Open
Abstract
Background Equine chorionic gonadotropin (eCG), which comprises highly glycosylated α-subunit and β-subunit, is a unique member of the glycoprotein hormone family as it elicits both follicle-stimulating hormone (FSH)-like and luteinizing hormone (LH)-like responses in non-equid species. To examine the biological function of glycosylated sites in eCG, the following glycosylation site mutants were constructed: eCGβ/αΔ56, substitution of Asn56 of α-subunit with Gln; eCGβ-D/α, deletion of the O-linked glycosylation site at the carboxyl-terminal peptide (CTP) region of the β-subunit; eCGβ-D/αΔ56, double mutant. The recombinant eCG (rec-eCG) mutants were expressed in Chinese hamster ovary suspension (CHO-S) cells. The FSH-like and LH-like activities of the mutants were examined using CHO-K1 cells expressing rat lutropin/CG receptor (rLH/CGR) and rat FSH receptor (rFSHR). Results Both rec-eCGβ/α and rec-eCGβ/αΔ56 were efficiently secreted into the CHO-S cell culture medium on day 1 post-transfection. However, the secretion of eCGβ-D/α and eCGβ-D/αΔ56, which lack approximately 12 O-linked glycosylation sites, was slightly delayed. The expression levels of all mutants were similar (200–250 mIU/mL) from days 3 to 7 post-transfection. The molecular weight of rec-eCGβ/α, rec-eCGβ/αΔ56 and rec-eCG β-D/α were in the ranges of 40–45, 37–42, and 34–36 kDa, respectively. Treatment with peptide-N-glycanase F markedly decreased the molecular weight to approximately 5–10 kDa. Rec-eCGβ/αΔ56 exhibited markedly downregulated LH-like activity. The signal transduction activity of both double mutants was completely impaired. This indicated that the glycosylation site at Asn56 of the α-subunit plays a pivotal role in the LH-like activity of eCG. Similarly, the FSH-like activity of the mutants was markedly downregulated. eCGβ-D/α exhibited markedly downregulated LH-like and FSH-like activities. Conclusions Rec-eCGβ/α exhibits potent biological activity in cells expressing rLH/CGR and rFSHR. The findings of this study suggest that the LH-like and FSH-like activities of eCG are regulated by the N-linked glycosylation site at Asn56 of the eCG α-subunit and/or by the O-linked glycosylation sites of the eCG β-subunit. These findings improved our understanding of the mechanisms underlying both LH-like and FSH-like activities of eCG.
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Affiliation(s)
- So-Yun Lee
- Animal Biotechnology, Graduate School of Future Convergence Technology, Institute of Genetic Engineering, Hankyong National University, Ansung, 17579, Korea
| | - Munkhzaya Byambaragchaa
- Animal Biotechnology, Graduate School of Future Convergence Technology, Institute of Genetic Engineering, Hankyong National University, Ansung, 17579, Korea
| | - Seung-Hee Choi
- Animal Biotechnology, Graduate School of Future Convergence Technology, Institute of Genetic Engineering, Hankyong National University, Ansung, 17579, Korea
| | - Han-Ju Kang
- Animal Biotechnology, Graduate School of Future Convergence Technology, Institute of Genetic Engineering, Hankyong National University, Ansung, 17579, Korea
| | - Myung-Hwa Kang
- Department of Food Science and Nutrition, Hoseo University, Asan, 31499, Korea
| | - Kwan-Sik Min
- Animal Biotechnology, Graduate School of Future Convergence Technology, Institute of Genetic Engineering, Hankyong National University, Ansung, 17579, Korea. .,School of Animal Life Biotechnology, Institute of Genetic Engineering, Hankyong National University, Ansung, 17579, Korea.
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Hua R, Liu J, Li Y, Fan Y, Zeng B, Geng G, Li Q. Novel Functional Recombinant Human Follicle-Stimulating Hormone Acquired from Goat Milk. J Agric Food Chem 2021; 69:2793-2804. [PMID: 33645971 DOI: 10.1021/acs.jafc.0c07208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An animal mammary bioreactor is regarded as an excellent biological system which is applied to produce large-scale recombinant proteins in milk. However, there are no effective methods to produce a large amount of some pharmaceutical proteins, such as human follicle-stimulating hormone (FSH), by large animal mammary gland bioreactors due to the fact that accumulation of excessive bioactive FSH might cause serious diseases in animals. Here, we report a novel strategy of preparing recombinant human FSH (rhFSH) from goat mammary glands, which could avoid the accumulation of bioactive FSH in goats. First, the single inactive FSHα and FSHβ subunits expressed in goat mammary epithelial cells and goat mammary glands were performed to reassemble in vitro and were found to self-assemble into a complete heterodimer rhFSH at 4 °C and pH 7.4. Further, a cyclic adenosine monophosphate (cAMP) induction assay showed that the cAMP levels in cell lysate of HEK 293/FSHR cells were increased by about 8-fold in reassembled rhFSH groups than that in the control group (P < 0.01). Pharmacokinetic analysis indicated that the reassembled rhFSH from goat mammary glands was comparable to that of the commercially available Gonal-F (P > 0.05). In addition, the increasing dose of reassembled rhFSH significantly promoted ovulation of mouse and ovary weight gain of Sprague Dawley rat compared with the control groups and maximum values were up to 3-fold (P < 0.01) and 2.8-fold (P < 0.01), respectively. The reassembled rhFSH showed a similar effect to Gonal-F in inducing expression of FSH target genes in vivo and activating the PI3K pathway in granulosa cells. Our study developed a novel method to produce rhFSH and provided the basis for preparing FSH by the goat mammary gland bioreactor with less health problems on the producing animals.
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Affiliation(s)
- Rongmao Hua
- College of Animal Science and Technology, Northwest A&F University, Yangling 712100, P. R. China
| | - Jianxi Liu
- Institute of Special Environmental Medicine, Nantong University, Nantong 226019, P. R. China
| | - Yuan Li
- College of Animal Science and Technology, Northwest A&F University, Yangling 712100, P. R. China
| | - Yan Fan
- College of Life Science, Jiangxi Science & Technology Normal University, Nanchang 330013, P. R. China
| | - Bin Zeng
- College of Life Science, Jiangxi Science & Technology Normal University, Nanchang 330013, P. R. China
| | - Guoxia Geng
- College of Veterinary Medicine, Northwest Agriculture and Forestry University, Yangling 712100, P. R. China
| | - Qingwang Li
- College of Animal Science and Technology, Northwest A&F University, Yangling 712100, P. R. China
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Byambaragchaa M, Kim JS, Park HK, Kim DJ, Hong SM, Kang MH, Min KS. Constitutive Activation and Inactivation of Mutations Inducing Cell Surface Loss of Receptor and Impairing of Signal Transduction of Agonist-Stimulated Eel Follicle-Stimulating Hormone Receptor. Int J Mol Sci 2020; 21:E7075. [PMID: 32992880 DOI: 10.3390/ijms21197075] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/23/2020] [Accepted: 09/23/2020] [Indexed: 12/17/2022] Open
Abstract
In the present study, we investigated the signal transduction of mutants of the eel follicle-stimulating hormone receptor (eelFSHR). Specifically, we examined the constitutively activating mutant D540G in the third intracellular loop, and four inactivating mutants (A193V, N195I, R546C, and A548V). To directly assess functional effects, we conducted site-directed mutagenesis to generate mutant receptors. We measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary (CHO-K1) cells and investigated cell surface receptor loss using an enzyme-linked immunosorbent assay in human embryonic kidney (HEK) 293 cells. The cells expressing eelFSHR-D540G exhibited a 23-fold increase in the basal cAMP response without agonist treatment. The cells expressing A193V, N195I, and A548V mutants had completely impaired signal transduction, whereas those expressing the R546C mutant exhibited little increase in cAMP responsiveness and a small increase in signal transduction. Cell surface receptor loss in the cells expressing inactivating mutants A193V, R546C, and A548V was clearly slower than in the cell expressing the wild-type eelFSHR. However, cell surface receptor loss in the cells expressing inactivating mutant N195I decreased in a similar manner to that of the cells expressing the wild-type eelFSHR or the activating mutant D540G, despite the completely impaired cAMP response. These results provide important information regarding the structure–function relationships of G protein-coupled receptors during signal transduction.
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