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Updated: Jul 15, 2026
10:13
Measuring G-protein-coupled Receptor Signaling via Radio-labeled GTP Binding
Published on: June 9, 2017
G-protein-coupled receptors: an update
B B Fredholm1, T Hökfelt, G Milligan
1Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. bertil.fredholm@ki.se
Acta Physiologica (Oxford, England)
|April 13, 2007
Summary
G protein-coupled receptors (GPCRs) are complex and form ensembles, influencing drug development. New research reveals novel signaling pathways and constitutive activity, offering new therapeutic strategies.
Area of Science:
- Biochemistry
- Pharmacology
- Molecular Biology
Background:
- G protein-coupled receptors (GPCRs), also known as 7-transmembrane (7-TM) receptors, are crucial cell surface proteins.
- GPCRs play significant roles in various physiological and pathophysiological processes.
- The mapping of GPCR ensembles across species highlights their importance in biological systems.
Purpose of the Study:
- To explore recent advancements and emerging complexities in GPCR research.
- To discuss the implications of GPCR multimeric ensembles for physiology and pharmacology.
- To highlight novel signaling pathways and constitutive activity of GPCRs.
Main Methods:
- Genetic targeting to clarify GPCR roles.
- Analysis of GPCR multimeric ensembles.
- Investigation of novel GPCR signaling pathways.
Main Results:
- GPCRs exist in multimeric ensembles, influencing their function.
- Some GPCRs exhibit constitutive activity, suggesting the utility of inverse agonists.
- GPCR activity varies significantly across tissues, enabling targeted drug action.
- Emerging evidence indicates GPCRs can signal through non-G-protein pathways.
Conclusions:
- GPCR research is revealing new levels of complexity, including receptor interactions and alternative signaling mechanisms.
- The constitutive activity and tissue-specific variations in GPCRs offer opportunities for developing more specific drugs.
- Understanding these complexities presents significant challenges and opportunities for basic scientists and the pharmaceutical industry.
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01:15G Protein-coupled Receptors
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
01:15G Protein-coupled Receptors
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
01:21G-protein Coupled Receptors
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
01:21G-protein Coupled Receptors
G-protein coupled receptors are ligand binding receptors that indirectly affect changes in the cell. The actual receptor is a single polypeptide that transverses the cell membrane seven times creating intracellular and extracellular loops. The extracellular loops create a ligand specific pocket which binds to neurotransmitters or hormones. The intracellular loops holds onto the G-protein.
01:30Transducer Mechanism: G Protein–Coupled Receptors
G Protein–Coupled Receptors (GPCRs) are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to various stimuli. GPCRs regulate critical physiological pathways and are excellent drug targets for treating diseases such as diabetes, cancer, obesity, depression, or Alzheimer's. Nearly 35% of approved drugs implement their therapeutic effects by selectively interacting with specific GPCRs.
GPCRs are also called heptahelical, 7TM, or...
GPCRs are also called heptahelical, 7TM, or...
01:22Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...