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Koklič T, Hrovat A, Guixà-González R, Rodríguez-Espigares I, Navio D, Frangež R, Uršič M, Kubale V, Plemenitaš A, Selent J, Šentjurc M, Vrecl M. Electron Paramagnetic Resonance Gives Evidence for the Presence of Type 1 Gonadotropin-Releasing Hormone Receptor (GnRH-R) in Subdomains of Lipid Rafts. Molecules 2021; 26:molecules26040973. [PMID: 33673080 PMCID: PMC7918721 DOI: 10.3390/molecules26040973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/02/2021] [Accepted: 02/08/2021] [Indexed: 11/16/2022] Open
Abstract
This study investigated the effect of type 1 gonadotropin releasing hormone receptor (GnRH-R) localization within lipid rafts on the properties of plasma membrane (PM) nanodomain structure. Confocal microscopy revealed colocalization of PM-localized GnRH-R with GM1-enriched raft-like PM subdomains. Electron paramagnetic resonance spectroscopy (EPR) of a membrane-partitioned spin probe was then used to study PM fluidity of immortalized pituitary gonadotrope cell line αT3-1 and HEK-293 cells stably expressing GnRH-R and compared it with their corresponding controls (αT4 and HEK-293 cells). Computer-assisted interpretation of EPR spectra revealed three modes of spin probe movement reflecting the properties of three types of PM nanodomains. Domains with an intermediate order parameter (domain 2) were the most affected by the presence of the GnRH-Rs, which increased PM ordering (order parameter (S)) and rotational mobility of PM lipids (decreased rotational correlation time (τc)). Depletion of cholesterol by methyl-β-cyclodextrin (methyl-β-CD) inhibited agonist-induced GnRH-R internalization and intracellular Ca2+ activity and resulted in an overall reduction in PM order; an observation further supported by molecular dynamics (MD) simulations of model membrane systems. This study provides evidence that GnRH-R PM localization may be related to a subdomain of lipid rafts that has lower PM ordering, suggesting lateral heterogeneity within lipid raft domains.
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Affiliation(s)
- Tilen Koklič
- Laboratory of Biophysics, Department of Condensed Matter Physics, Jožef Stefan Institute, 1000 Ljubljana, Slovenia; (T.K.); (M.Š.)
| | - Alenka Hrovat
- Veterinary Faculty, Institute of Preclinical Sciences, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (A.H.); (R.F.); (M.U.); (V.K.)
| | - Ramon Guixà-González
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Hospital del Mar Medical Research Institute (IMIM), Pompeu Fabra University (UPF), 08003 Barcelona, Spain; (R.G.-G.); (I.R.-E.); (D.N.); (J.S.)
- Laboratory of Biomolecular Research, Paul Scherrer Institute (PSI), 5232 Villigen, Switzerland
- Condensed Matter Theory Group, PSI, 5232 Villigen, Switzerland
| | - Ismael Rodríguez-Espigares
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Hospital del Mar Medical Research Institute (IMIM), Pompeu Fabra University (UPF), 08003 Barcelona, Spain; (R.G.-G.); (I.R.-E.); (D.N.); (J.S.)
| | - Damaris Navio
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Hospital del Mar Medical Research Institute (IMIM), Pompeu Fabra University (UPF), 08003 Barcelona, Spain; (R.G.-G.); (I.R.-E.); (D.N.); (J.S.)
| | - Robert Frangež
- Veterinary Faculty, Institute of Preclinical Sciences, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (A.H.); (R.F.); (M.U.); (V.K.)
| | - Matjaž Uršič
- Veterinary Faculty, Institute of Preclinical Sciences, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (A.H.); (R.F.); (M.U.); (V.K.)
| | - Valentina Kubale
- Veterinary Faculty, Institute of Preclinical Sciences, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (A.H.); (R.F.); (M.U.); (V.K.)
| | - Ana Plemenitaš
- Faculty of Medicine, Institute of Biochemistry and Molecular Genetics, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Hospital del Mar Medical Research Institute (IMIM), Pompeu Fabra University (UPF), 08003 Barcelona, Spain; (R.G.-G.); (I.R.-E.); (D.N.); (J.S.)
| | - Marjeta Šentjurc
- Laboratory of Biophysics, Department of Condensed Matter Physics, Jožef Stefan Institute, 1000 Ljubljana, Slovenia; (T.K.); (M.Š.)
| | - Milka Vrecl
- Veterinary Faculty, Institute of Preclinical Sciences, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (A.H.); (R.F.); (M.U.); (V.K.)
- Correspondence: ; Tel.: +386-1-477-9118
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Davis TL. Nonclassical actions of estradiol-17beta are not detectable in the alphaT3-1 and LbetaT2 immortalized gonadotrope cell lines†. Biol Reprod 2019; 101:791-799. [PMID: 31290547 DOI: 10.1093/biolre/ioz118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 06/24/2019] [Accepted: 07/05/2019] [Indexed: 11/13/2022] Open
Abstract
The immortalized mouse gonadotrope cell lines alphaT3-1 and LbetaT2 cells have been a substitute model for primary gonadotropes. These cell lines have provided a homogeneous cell population, as compared to the dissociated anterior pituitaries, which contain a heterogeneous population of cells potentially responsive to estradiol-17beta (E2). Nonclassical actions of E2 assumed to occur through the plasma membrane estrogen receptor 1 (ESR1, also known as ERalpha). These actions have included inhibition of gonadotropin-releasing hormone (GnRH)-induced increases in intracellular calcium concentrations and phosphorylation of p44/42 mitogen-activated protein kinase (ERK-1/2) in ovine pituitaries including primary gonadotropes in vitro. The objective of the present experiment was to determine if alphaT3-1 and LbetaT2 are cell models with limitations to examine the nonclassical actions of E2 occurring in gonadotropes. Experiments were conducted to determine if the cells have ESR1 at the plasma membrane using biotinylation cell and isolation of surface protein and staining with a fluorescently labeled E2 conjugate. The alphaT3-1 cells contain ESR1 associated with but not enriched within lipid rafts of the plasma membrane and do not translocate to lipid rafts upon binding of E2. In contrast, LbetaT2 cells lack ESR1 associated with the plasma membrane. Pretreatment with E2 did not cause inhibition of GnRH-stimulated increases in intracellular concentrations of calcium for either cell type. Phosphorylation of ERK-1/2 was not stimulated by E2 in either cell type. Although these cells lines have been used extensively to study GnRH signaling, in vitro or in vivo effects of nonclassical actions of E2 cannot be replicated in either cell line.
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Affiliation(s)
- Tracy L Davis
- Department of Biology, Wingate University, Wingate, North Carolina, USA
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Pratap A, Garner KL, Voliotis M, Tsaneva-Atanasova K, McArdle CA. Mathematical modeling of gonadotropin-releasing hormone signaling. Mol Cell Endocrinol 2017; 449:42-55. [PMID: 27544781 PMCID: PMC5446263 DOI: 10.1016/j.mce.2016.08.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/09/2016] [Accepted: 08/11/2016] [Indexed: 12/12/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) acts via G-protein coupled receptors on pituitary gonadotropes to control reproduction. These are Gq-coupled receptors that mediate acute effects of GnRH on the exocytotic secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), as well as the chronic regulation of their synthesis. GnRH is secreted in short pulses and GnRH effects on its target cells are dependent upon the dynamics of these pulses. Here we overview GnRH receptors and their signaling network, placing emphasis on pulsatile signaling, and how mechanistic mathematical models and an information theoretic approach have helped further this field.
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Affiliation(s)
- Amitesh Pratap
- Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Kathryn L Garner
- Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Margaritis Voliotis
- EPSRC Centre for Predictive Modeling in Healthcare, University of Exeter, Exeter, EX4 4QF, UK
| | - Krasimira Tsaneva-Atanasova
- Department of Mathematics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, UK; EPSRC Centre for Predictive Modeling in Healthcare, University of Exeter, Exeter, EX4 4QF, UK
| | - Craig A McArdle
- Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK.
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Janjic MM, Stojilkovic SS, Bjelobaba I. Intrinsic and Regulated Gonadotropin-Releasing Hormone Receptor Gene Transcription in Mammalian Pituitary Gonadotrophs. Front Endocrinol (Lausanne) 2017; 8:221. [PMID: 28928715 PMCID: PMC5591338 DOI: 10.3389/fendo.2017.00221] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/16/2017] [Indexed: 12/14/2022] Open
Abstract
The hypothalamic decapeptide gonadotropin-releasing hormone (GnRH), acting via its receptors (GnRHRs) expressed in pituitary gonadotrophs, represents a critical molecule in control of reproductive functions in all vertebrate species. GnRH-activated receptors regulate synthesis of gonadotropins in a frequency-dependent manner. The number of GnRHRs on the plasma membrane determines the responsiveness of gonadotrophs to GnRH and varies in relation to age, sex, and physiological status. This is achieved by a complex control that operates at transcriptional, translational, and posttranslational levels. This review aims to overview the mechanisms of GnRHR gene (Gnrhr) transcription in mammalian gonadotrophs. In general, Gnrhr exhibits basal and regulated transcription activities. Basal Gnrhr transcription appears to be an intrinsic property of native and immortalized gonadotrophs that secures the presence of a sufficient number GnRHRs to preserve their functionality independently of the status of regulated transcription. On the other hand, regulated transcription modulates GnRHR expression during development, reproductive cycle, and aging. GnRH is crucial for regulated Gnrhr transcription in native gonadotrophs but is ineffective in immortalized gonadotrophs. In rat and mouse, both basal and GnRH-induced Gnrhr transcription rely primarily on the protein kinase C signaling pathway, with subsequent activation of mitogen-activated protein kinases. Continuous GnRH application, after a transient stimulation, shuts off regulated but not basal transcription, suggesting that different branches of this signaling pathway control transcription. Pituitary adenylate cyclase-activating polypeptide, but not activins, contributes to the regulated transcription utilizing the protein kinase A signaling pathway, whereas a mechanisms by which steroid hormones modulate Gnrhr transcription has not been well characterized.
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Affiliation(s)
- Marija M. Janjic
- Department of Neurobiology, Institute for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, Serbia
| | - Stanko S. Stojilkovic
- Section on Cellular Signaling, Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Ivana Bjelobaba
- Department of Neurobiology, Institute for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, Serbia
- *Correspondence: Ivana Bjelobaba,
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West C, Hanyaloglu AC. Minireview: Spatial Programming of G Protein-Coupled Receptor Activity: Decoding Signaling in Health and Disease. Mol Endocrinol 2015; 29:1095-106. [PMID: 26121235 DOI: 10.1210/me.2015-1065] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Probing the multiplicity of hormone signaling via G protein-coupled receptors (GPCRs) has demonstrated the complex signal pathways that underlie the multiple functions these receptors play in vivo. This is highly pertinent for the GPCRs key in reproduction and pregnancy that are exposed to cyclical and dynamic changes in their extracellular milieu. How such functional pleiotropy in GPCR signaling is translated to specific downstream cellular responses, however, is largely unknown. Emerging data strongly support mechanisms for a central role of receptor location in signal regulation via membrane trafficking. In this review, we discuss current progress in our understanding of the role membrane trafficking plays in location control of GPCR signaling, from organized plasma membrane signaling microdomains, potentially provided by both distinct endocytic and exocytic pathways, to more recent evidence for spatial control within the endomembrane system. Application of these emerging mechanisms in their relevance to GPCR activity in physiological and pathophysiological conditions will also be discussed, and in improving therapeutic strategies that exploits these mechanisms in order to program highly regulated and distinct signaling profiles.
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Affiliation(s)
- Camilla West
- Institute of Reproductive Biology and Development, Department of Surgery and Cancer, Imperial College London, London, W12 0NN, United Kingdom
| | - Aylin C Hanyaloglu
- Institute of Reproductive Biology and Development, Department of Surgery and Cancer, Imperial College London, London, W12 0NN, United Kingdom
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Schang A. Inside and outside the pituitary: comparative analysis of Gnrhr expression provides insight into the mechanisms underlying the evolution of gene expression. J Neuroendocrinol 2015; 27:177-86. [PMID: 25556311 DOI: 10.1111/jne.12253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 11/18/2014] [Accepted: 12/27/2014] [Indexed: 02/06/2023]
Abstract
DNA cis-acting elements involved in gene regulation may actively contribute to adaptation processes because they are submitted to lower evolutionary constraints than coding DNA. In this regard, comparisons of the mechanisms underlying basal and regulated Gnrhr expression have revealed some features that promote stable and consistent Gnrhr expression in pituitary gonadotroph cells in different species. The presence of two divergent SF1 (NR5A1) response elements in all analysed mammalian Gnrhr promoters probably comprises one of the features that ensures reliable expression in the pituitary. By contrast, in other tissues, such as the hippocampus and testis, our analyses revealed dissimilar levels of Gnrhr expression among species. Indeed, Gnrhr was consistently expressed after birth in the rat but not the mouse hippocampus. Similar discrepancies were observed in foetal and adult testes. The ability of the rat promoter to drive reporter gene expression in the hippocampus and testis of transgenic mice just as it naturally directs the expression of the endogenous Gnrhr in rats strongly suggests that regulatory DNA sequences contained species-specific instructions prevailing over other controls. The major conclusion emerging from these studies is that Gnrhr promoter sequences are mainly responsible for directing transcriptional programmes and play a predominant role over the species-specific cell environment.
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Affiliation(s)
- Al Schang
- Sorbonne Paris Cité, Biologie Fonctionnelle et Adaptative, Université Paris Diderot, Paris 7, CNRS 8251, Paris, France; Sorbonne Paris Cité, Epigénétique et Destin Cellulaire, Universite Paris Diderot, Paris 7, CNRS 7216, Paris, France
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Navratil AM, Bliss SP, Roberson MS. Membrane rafts and GnRH receptor signaling. Brain Res 2010; 1364:53-61. [PMID: 20836995 DOI: 10.1016/j.brainres.2010.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 08/31/2010] [Accepted: 09/02/2010] [Indexed: 10/19/2022]
Abstract
The binding of hypothalamic gonadotropin-releasing hormone (GnRH) to the pituitary GnRH receptor (GnRHR) is essential for reproductive function by stimulating the synthesis and secretion of gonadotropic hormones, luteinizing hormone (LH) and follicle stimulating hormone (FSH). Engagement of the GnRHR by GnRH initiates a complex series of signaling events that include the activation of various mitogen-activated protein kinase (MAPK) pathways, including extracellular signal-regulated kinase (ERK). GnRHR signaling is thought to initiate within specialized microdomains in the plasma membrane termed membrane rafts. These microdomains are enriched in sphingolipid and cholesterol and are believed to be highly dynamic organizing centers for receptors and their cognate signaling molecules associated with the plasma membrane. Within this review we discuss the composition and role of membrane rafts in cell signaling and examine evidence that the mammalian type I GnRHR is constitutively and exclusively localized to these membrane microdomains in various experimental models. We conclude that membrane raft composition and organization potentially underlie the functional ability of GnRH to elicit the assembly of multi-protein signaling complexes necessary for downstream signaling to the ERK pathway that ultimately is critical for controlling fertility.
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Affiliation(s)
- Amy M Navratil
- Department of Biomedical Sciences, T4-018 Veterinary Research Tower, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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Filipp D, Moemeni B, Ferzoco A, Kathirkamathamby K, Zhang J, Ballek O, Davidson D, Veillette A, Julius M. Lck-dependent Fyn activation requires C terminus-dependent targeting of kinase-active Lck to lipid rafts. J Biol Chem 2008; 283:26409-22. [PMID: 18660530 DOI: 10.1074/jbc.m710372200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanisms regulating the activation and delivery of function of Lck and Fyn are central to the generation of the most proximal signaling events emanating from the T cell antigen receptor (TcR) complex. Recent results demonstrate that lipid rafts (LR) segregate Lck and Fyn and play a fundamental role in the temporal and spatial coordination of their activation. Specifically, TcR-CD4 co-aggregation-induced Lck activation outside LR results in Lck translocation to LR where the activation of LR-resident Fyn ensues. Here we report a structure-function analysis toward characterizing the mechanism supporting Lck partitioning to LR and its capacity to activate co-localized Fyn. Using NIH 3T3 cells ectopically expressing FynT, we demonstrate that only LR-associated, kinase-active (Y505F)Lck reciprocally co-immunoprecipitates with and activates Fyn. Mutational analyses revealed a profound reduction in the formation of Lck-Fyn complexes and Fyn activation, using kinase domain mutants K273R and Y394F of (Y505F)Lck, both of which have profoundly compromised kinase activity. The only kinase-active Lck mutants tested that revealed impaired physical and enzymatic engagement with Fyn were those involving truncation of the C-terminal sequence YQPQP. Remarkably, sequential truncation of YQPQP resulted in an increasing reduction of kinase-active Lck partitioning to LR, in both fibroblasts and T cells. This in turn correlated with an ablation of the capacity of these truncates to enhance TcR-mediated interleukin-2 production. Thus, Lck-dependent Fyn activation is predicated by proximity-mediated transphosphorylation of the Fyn kinase domain, and targeting kinase-active Lck to LR is dependent on the C-terminal sequence QPQP.
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Affiliation(s)
- Dominik Filipp
- Sunnybrook Research Institute and the Department of Immunology, University of Toronto, Toronto, Ontario M4N 3M5, Canada
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Kubale V, Abramović Z, Pogacnik A, Heding A, Sentjurc M, Vrecl M. Evidence for a role of caveolin-1 in neurokinin-1 receptor plasma-membrane localization, efficient signaling, and interaction with beta-arrestin 2. Cell Tissue Res 2007; 330:231-45. [PMID: 17713785 DOI: 10.1007/s00441-007-0462-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 07/04/2007] [Indexed: 10/22/2022]
Abstract
This study was focused on the relationship between the plasma-membrane localization of neurokinin-1 receptor (NK1-R) and its endocytic and signaling properties. First, we employed electron paramagnetic resonance (EPR) to study the domain structure of HEK-293 cells and NK1-R microlocalization. EPR spectra and the GHOST condensation routine demonstrated that NK1-R was distributed in a well-ordered domain of HEK-293 cells possibly representing lipid raft/caveolae microdomains, whereas the impairment of caveolae changed the NK1-R plasma-membrane distribution. Internalization and second messenger assays combined with bioluminescence resonance energy transfer were employed subsequently to evaluate the functional importance of the NK1-R microlocalization in lipid raft/caveolae microdomains. The internalization pattern was delineated through the use of dominant-negative mutants (DNM) of caveolin-1 S80E (Cav1 S80E), dynamin-1 K44A (Dyn K44A), and beta-arrestin (beta-arr 319-418) and by means of cell lines that expressed various endogenous levels of beta-arrestins. NK1-R displayed rapid internalization that was substantially reduced by DNMs of dynamin-1 and beta-arrestin and even more profoundly in cells lacking both beta-arrestin1 and beta-arrestin2. These internalization data were highly suggestive of the predominant use of the clathrin-mediated pathway by NK1-R, even though NK1-R tended to reside constitutively in lipid raft/caveolae microdomains. Evidence was also obtained that the proper clustering of the receptor in these microdomains was important for effective agonist-induced NK1-R signaling and for its interaction with beta-arrestin2.
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Affiliation(s)
- Valentina Kubale
- Institute of Anatomy, Histology & Embryology, Veterinary Faculty, University of Ljubljana, Gerbiceva 60, SI-1000, Ljubljana, Slovenia
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Current World Literature. Curr Opin Obstet Gynecol 2007; 19:289-96. [PMID: 17495648 DOI: 10.1097/gco.0b013e3281fc29db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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