Investigation of the effect of GPCR oligomerization on the GNAi1 protein homodimerization in live cells using FRET

Nalli, Enise
G-Protein Coupled Receptors (GPCR) are membrane proteins that pass the cell membrane seven times. In classical GPCR signaling pathways, one GPCR-one heterotrimeric G-protein interaction model is enough to transmit the signal to effector proteins. Studies since 2000 showed that one GPCR dimer-one heterotrimeric G-protein interaction model is more likely, and GPCRs having homo- /hetero- dimers interact with a single G⍺-protein. Recently, studies on GPCRs indicated that more than two receptors interact to form active receptor oligomers during signal transduction. Navarro et al. showed that within a heterotetrameric receptor complex, formed by the dimerization of the dimers, the G proteins interacting with the dimers were brought into close proximity (Navarro et al., 2018). Furthermore, studies with Ras proteins, which are members of the G-protein family, have shown that these proteins form dimers playing important roles in various signaling pathways. More recently, a member of our Lab., Özge Atay, has shown the physical interaction of Gαi1 proteins on the cell membrane. However, it is still not vi clear whether the Gαi1 protein homodimerization is a result of the formation of receptor tetramers or if the Gαi1 homodimers form independently of the receptors. Receptor independent G-protein dimerization might play a role in stabilizing the receptor tetramers. In order to answer this question, Förster Resonance Energy Transfer (FRET) method was used to quantitatively investigate the effect of GPCR oligomerization on the Gαi1 homodimerization under two conditions: (1) blocking GPCR-Gαi1 interaction with Gαi1-specific minigenes and (2) receptor oligomerization by agonist (Quinpirole) treatment.


Balkan, Seyda Tuğçe; Son, Çağdaş Devrim; Küçük Baloğlu, Fatma; Department of Biochemistry (2021-8-11)
GPCR’s are seven-transmembrane receptors that transmit external signals to the intracellular environment via secondary messenger systems through heterotrimeric G proteins. Heterotrimeric G proteins consist of α and β-γ subunits. Until recent years, scientists thought that GPCR signal transduction occurs between one GPCR and one heterotrimeric G protein; however, recently, it has been shown that GPCR’s can make oligomers. Oligomerization of GPCR allows cells to tune the intensity of the signal and respond ap...
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Çınar, Muazzez Çelebi; Son, Çağdaş Devrim; Department of Molecular Biology and Genetics (2019)
G protein-coupled receptors (GPCRs) are one of the largest and the most significant membrane receptor families in eukaryotes. They transmit extracellular stimuli to the inside of the cell by undergoing conformational changes. GPCRs can recognize a diversity of extracellular ligands including hormones, neurotransmitters, odorants, photons, and ions. These receptors are associated with a variety of diseases in humans such as cancer and central nervous system disorders, and can be proclaimed as one of the most...
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G-protein coupled receptors (GPCRs) are a class of integral membrane receptor proteins that are characterized by a signature seven-transmembrane (7-TM) configuration. The alpha-factor receptor (Ste2p) from Saccharomyces cerevisiae is a GPCR that, upon binding of a peptide ligand, transduces a signal to initiate a cascade of events leading to the mating of haploid yeast cells. This study summarizes the application of affinity purification and of matrix-assisted laser-desorption ionization time-of-flight (MAL...
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The physiological O-2 microenvironment of mesenchymal stem cells (MSCs) and osteoblasts and the dimensionality of a substrate are known to be important in regulating cell phenotype and function. By providing the physiologically normoxic environments of bone marrow (5%) and matrix (12%), we assessed their potential to maintain stemness, induce osteogenic differentiation, and enhance the material properties in the micropatterned collagen/silk fibroin scaffolds that were produced in 2D or 3D. Expression of ost...
In Vivo detection of GPCR dimerizations in saccharomyces cerevisiae using FRET and BIFC
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G protein-coupled receptors (GPCRs) are a class of membrane proteins that are composed of seven transmembrane domain and mediate physiological response to a diverse array of stimuli. In eukaryotic microorganisms, GPCRs regulate cell growth, development, morphogenesis, motility, and life span. In higher eukaryotic organisms as humans, they mediate the action of hundreds of peptide hormones, sensory stimuli, odorants, neurotransmitters, and chemokine. Due to their wide spectrum of action mechanisms, GPCRs are...
Citation Formats
E. Nalli, “Investigation of the effect of GPCR oligomerization on the GNAi1 protein homodimerization in live cells using FRET,” M.S. - Master of Science, Middle East Technical University, 2022.