scholarly journals Structures in G proteins important for subtype selective receptor binding and subsequent activation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Volker Jelinek ◽  
Nadja Mösslein ◽  
Moritz Bünemann
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein Complexes ◽  
Heterotrimeric G Proteins ◽  
Structural Determinants ◽  
C Terminus ◽  
Subsequent Activation ◽  
The Stability ◽  
Subtype Selective ◽  
G Protein Coupled

AbstractG protein-coupled receptors (GPCRs) selectively couple to specific heterotrimeric G proteins comprised of four subfamilies in order to induce appropriate physiological responses. However, structural determinants in Gα subunits responsible for selective recognition by approximately 800 human GPCRs have remained elusive. Here, we directly compare the influence of subtype-specific Gα structures on the stability of GPCR-G protein complexes and the activation by two Gq-coupled receptors. We used FRET-assays designed to distinguish multiple Go and Gq-based Gα chimeras in their ability to be selectively bound and activated by muscarinic M3 and histaminic H1 receptors. We identify the N-terminus including the αN/β1-hinge, the β2/β3-loop and the α5 helix of Gα to be key selectivity determinants which differ in their impact on selective binding to GPCRs and subsequent activation depending on the specific receptor. Altogether, these findings provide new insights into the molecular basis of G protein-coupling selectivity even beyond the Gα C-terminus.

scholarly journals Comprehensive analysis of heterotrimeric G-protein complex diversity and their interactions with GPCRs in solution

2015 ◽  
Vol 112 (11) ◽  
pp. E1181-E1190 ◽  
Author(s):  
Matthias Hillenbrand ◽  
Christian Schori ◽  
Jendrik Schöppe ◽  
Andreas Plückthun
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Conformational Changes ◽  
Protein Complex ◽  
Protein Complexes ◽  
Heterotrimeric G Proteins ◽  
Agonist Binding ◽  
Transient Nature ◽  
The Stability ◽  
Neurotensin Receptor 1

Agonist binding to G-protein–coupled receptors (GPCRs) triggers signal transduction cascades involving heterotrimeric G proteins as key players. A major obstacle for drug design is the limited knowledge of conformational changes upon agonist binding, the details of interaction with the different G proteins, and the transmission to movements within the G protein. Although a variety of different GPCR/G protein complex structures would be needed, the transient nature of this complex and the intrinsic instability against dissociation make this endeavor very challenging. We have previously evolved GPCR mutants that display higher stability and retain their interaction with G proteins. We aimed at finding all G-protein combinations that preferentially interact with neurotensin receptor 1 (NTR1) and our stabilized mutants. We first systematically analyzed by coimmunoprecipitation the capability of 120 different G-protein combinations consisting of αi1or αsLand all possible βγ-dimers to form a heterotrimeric complex. This analysis revealed a surprisingly unrestricted ability of the G-protein subunits to form heterotrimeric complexes, including βγ-dimers previously thought to be nonexistent, except for combinations containing β5. A second screen on coupling preference of all G-protein heterotrimers to NTR1 wild type and a stabilized mutant indicated a preference for those Gαi1βγ combinations containing γ1and γ11. Heterotrimeric G proteins, including combinations believed to be nonexistent, were purified, and complexes with the GPCR were prepared. Our results shed new light on the combinatorial diversity of G proteins and their coupling to GPCRs and open new approaches to improve the stability of GPCR/G-protein complexes.

scholarly journals Variable G protein determinants of GPCR coupling selectivity

2019 ◽  
pp. 201905993 ◽  
Author(s):  
Najeah Okashah ◽  
Qingwen Wan ◽  
Soumadwip Ghosh ◽  
Manbir Sandhu ◽  
Asuka Inoue ◽  
...  
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Heterotrimeric G Proteins ◽  
C Terminus ◽  
General Rules ◽  
Primary Determinant ◽  
Bret Assay ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) activate four families of heterotrimeric G proteins, and individual receptors must select a subset of G proteins to produce appropriate cellular responses. Although the precise mechanisms of coupling selectivity are uncertain, the Gα subunit C terminus is widely believed to be the primary determinant recognized by cognate receptors. Here, we directly assess coupling between 14 representative GPCRs and 16 Gα subunits, including one wild-type Gα subunit from each of the four families and 12 chimeras with exchanged C termini. We use a sensitive bioluminescence resonance energy transfer (BRET) assay that provides control over both ligand and nucleotide binding, and allows direct comparison across G protein families. We find that the Gs- and Gq-coupled receptors we studied are relatively promiscuous and always couple to some extent to Gi1 heterotrimers. In contrast, Gi-coupled receptors are more selective. Our results with Gα subunit chimeras show that the Gα C terminus is important for coupling selectivity, but no more so than the Gα subunit core. The relative importance of the Gα subunit core and C terminus is highly variable and, for some receptors, the Gα core is more important for selective coupling than the C terminus. Our results suggest general rules for GPCR-G protein coupling and demonstrate that the critical G protein determinants of selectivity vary widely, even for different receptors that couple to the same G protein.

scholarly journals Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 222
Author(s):  
Agnieszka Polit ◽  
Paweł Mystek ◽  
Ewa Błasiak
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Lipid Membranes ◽  
Signaling Proteins ◽  
Heterotrimeric G Proteins ◽  
Membrane Attachment ◽  
The Individual ◽  
Multicellular Organisms ◽  
G Protein Coupled

In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein–lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.

scholarly journals Signaling from G Protein-coupled Receptors to ERK5/Big MAPK 1 Involves Gαqand Gα12/13Families of Heterotrimeric G Proteins

2000 ◽  
Vol 275 (28) ◽  
pp. 21730-21736 ◽  
Author(s):  
Shigetomo Fukuhara ◽  
Maria Julia Marinissen ◽  
Mario Chiariello ◽  
J. Silvio Gutkind
Keyword(s):  
G Protein ◽  
G Proteins ◽  
G Protein Coupled Receptors ◽  
Heterotrimeric G Proteins ◽  
G Protein Coupled

Science Signaling Podcast for 12 April 2016: G proteins in auriculo-condylar syndrome

2016 ◽  
Vol 9 (423) ◽  
pp. pc9-pc9
Author(s):  
Mikel Garcia-Marcos ◽  
Annalisa M. VanHook
Keyword(s):  
Enzymatic Activity ◽  
G Protein ◽  
G Proteins ◽  
Heterotrimeric G Proteins ◽  
Craniofacial Abnormalities ◽  
Research Article ◽  
Neural Crest Development ◽  
Mutant Forms ◽  
Endothelin Type A Receptor ◽  
G Protein Coupled

AbstractThis Podcast features an interview with Mikel Garcia-Marcos, author of a Research Article that appears in the 12 April 2016 issue of Science Signaling, about how mutations in a G protein cause auriculo-condylar syndrome (ACS). ACS is caused by mutations that affect signaling through the endothelin type A receptor (ETAR) and is characterized by craniofacial abnormalities resulting from defects in neural crest development. ETAR is a G protein–coupled receptor (GPCR) that signals primarily through heterotrimeric G proteins containing Gαq/11, but mutations in Gαi3 are also associated with ACS. Marivin et al. found that ETAR coupled to ACS-associated mutant forms of Gαi3 instead of coupling to Gαq/11. These mutant forms of Gαi3 lacked enzymatic activity and thus blocked ETAR signaling.Listen to Podcast

scholarly journals II. Regulation of neuropeptide receptors in enteric neurons

1998 ◽  
Vol 274 (5) ◽  
pp. G792-G796
Author(s):  
Karen McConalogue ◽  
Nigel W. Bunnett
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Target Cell ◽  
Biological Effects ◽  
G Protein Coupled Receptors ◽  
Enteric Neurons ◽  
Heterotrimeric G Proteins ◽  
High Affinity ◽  
Neuropeptide Receptors ◽  
G Protein Coupled

Neuropeptides exert their diverse biological effects by interacting with G protein-coupled receptors (GPCRs). In this review we address the question, What regulates the ability of a target cell, in particular a neuron, to respond to a neuropeptide? Available evidence from studies of many GPCRs in reconstituted systems and transfected cell lines indicates that much of this regulation occurs at the level of the receptor and serves to alter the capacity of the receptor to bind ligands with high affinity and to couple to heterotrimeric G proteins. Although some of the knowledge gained from these studies is applicable to the regulation of neuropeptide receptors on neurons, at present there are far more questions than answers.

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