How activated receptors couple to G proteins

Hamm, Heidi E.

doi:10.1073/pnas.011099798

Cited by 197 publications

(163 citation statements)

References 36 publications

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“…Cellular signaling by GPCRs involves their activation upon binding to ligands present in the extracellular environment and the subsequent transduction of signals to the interior of the cell through concerted changes in their transmembrane domain structure [4]. The major paradigm in this signal transduction process is that stimulation of GPCRs leads to the recruitment and activation of heterotrimeric GTP-binding proteins (G-proteins) [5]. These initial events, fundamental to all types of GPCR signaling, occur at the plasma membrane via protein-protein interactions.…”

Section: Introductionmentioning

confidence: 99%

The human serotonin1A receptor exhibits G-protein-dependent cell surface dynamics

Pucadyil

Chattopadhyay

2006

Glycoconj J

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Seven transmembrane domain G-protein-coupled receptors constitute the largest family of proteins in mammals. Signal transduction events mediated by such receptors are the primary means by which cells communicate with and respond to their external environment. The major paradigm in this signal transduction process is that stimulation of the receptor leads to the recruitment and activation of heterotrimeric GTP-binding proteins. These initial events, which are fundamental to all types of G-protein-coupled receptor signaling, occur at the plasma membrane via protein-protein interactions. As a result, the dynamics of the activated receptor on cell surfaces represents an important determinant in its encounter with G-proteins, and has significant impact on the overall efficiency of the signal transduction process. We have monitored the cell surface dynamics of the serotonin 1A receptor, an important member of the G-protein-coupled receptor superfamily, in relation to its interaction with G-proteins. Fluorescence recovery after photobleaching experiments carried out with the receptor tagged to the enhanced yellow fluorescent protein indicate that G-protein activation alters the diffusion properties of the receptor in a manner suggesting the activation process leads to dissociation of G-proteins from the receptor. This result demonstrates that the cell surface dynamics of the serotonin 1A receptor is modulated in a G-protein-dependent manner. Importantly, this result could provide the basis for a sensitive and powerful approach to assess receptor/ G-protein interaction in an intact cellular environment.

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Section: Introductionmentioning

confidence: 99%

The human serotonin1A receptor exhibits G-protein-dependent cell surface dynamics

Pucadyil

Chattopadhyay

2006

Glycoconj J

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“…The LRG complex on beads is only stable when the pocket is empty and rapidly disassembles when either GDP or GTP are added. Thus the ternary complex formed in live cells survives for the short duration of the dissociative interchange between GDP and GTP [3,4].…”

Section: Guanine Nucleotide Activation Of the Heterotrimeric Gαβγ Commentioning

confidence: 99%

“…In cells, the ternary complex of ligand, GPCR, and heterotrimeric G protein complexes, has a very short lifetime, which is regulated by the kinetics of nucleotide exchange between the inactive GDP-bound form and the active GTP-bound form [3,33]. The exchange is initiated by the contact between the heterotrimeric G protein entity and a ligand activated receptor.…”

Section: How Ligand Activated Gpcrs Effect the Guanine Nucleotide Excmentioning

confidence: 99%

“…The ternary complex thus formed survives for the short duration of the dissociative interchange between GDP and GTP under rapid mass transfer considerations. The mechanism by which ligand activated GPCRs catalyze the exchange of GDP for GTP is not clear [3]. It is however believed to involve three flexible regions designated switch I, switch II, and switch III on the α subunit that have been shown to adopt different conformations in the presence of GDP, GTPγS, and other nucleotide adducts and analogs [41,42].…”

Section: How Ligand Activated Gpcrs Effect the Guanine Nucleotide Excmentioning

confidence: 99%

“…Currently, the consensus model of G protein activation involves the exchange of GDP for GTP catalyzed by ligand-activated GPCR results in the dissociation of the G protein heterotrimer into separate α and βγ subunits which then interact independently with their cognate effectors [3,4]. However, more recent experimental evidence has led to questions about the absolute necessity of including subunit dissociation as an element of activation.…”

Section: Introductionmentioning

confidence: 99%

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Rapid-mix flow cytometry measurements of subsecond regulation of G protein-coupled receptor ternary complex dynamics by guanine nucleotides

Buranda

Simons

et al. 2007

Analytical Biochemistry

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We have used rapid mix flow cytometry to analyze the early subsecond dynamics of the disassembly of ternary complexes of G-protein coupled receptors (GPCRs) immobilized on beads to examine individual steps associated with guanine nucleotide activation. Our earlier studies suggested that the slow dissociation of Gα and Gβγ subunits was unlikely to be an essential component of cell activation. However, these studies did not have adequate time resolution to define precisely the disassembly kinetics. Ternary complexes were assembled using three formyl peptide receptor constructs (wild type, FPR-Gα i2 fusion, and FPR-GFP fusion) and two isotypes of the α subunit (α i2 and α i3 ) and βγ dimer (β 1 γ 2 and β 4 γ 2 ). At saturating nucleotide levels, the disassembly of a significant fraction of ternary complexes occurred on a subsecond time frame for α i2 complexes and τ 1/2 ≤ 4 sec for α i3 complexes, time scales which are compatible with cell activation. β 1 γ 2 isotype complexes were generally more stable than β 4 γ 2 associated complexes. The comparison of the three constructs however proved that the fast step was associated with the separation of receptor and G protein and that the dissociation of the ligand or of the α and βγ subunits was slower. These results are compatible with a cell activation model involving G protein conformational changes rather than disassembly of Gαβγ heterotrimer.

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Crystal Structure of Rhodopsin: A G-Protein-Coupled Receptor

2002

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Shedding light on GPCRs: The crystal structure of rhodopsin, determined at 2.8 Å resolution, shows the major molecular structural features characteristic of G‐protein‐coupled receptors (see figure). The seven transmembrane helices are aligned roughly perpendicular to the membrane plane, with the binding surface for G proteins located on the cytoplasmic surface. The retinal chromophore important for photon absorption in this vision system protein is completely buried in the protein. The structure of the ground state molecule provides a base for understanding the structural and functional ramifications associated with signal transduction in the retina.

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How activated receptors couple to G proteins

Cited by 197 publications

References 36 publications

The human serotonin1A receptor exhibits G-protein-dependent cell surface dynamics

The human serotonin1A receptor exhibits G-protein-dependent cell surface dynamics

Rapid-mix flow cytometry measurements of subsecond regulation of G protein-coupled receptor ternary complex dynamics by guanine nucleotides

Crystal Structure of Rhodopsin: A G-Protein-Coupled Receptor

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