Related Experiment Video

Updated: Jul 10, 2026

Measuring G-protein-coupled Receptor Signaling via Radio-labeled GTP Binding
10:13

Measuring G-protein-coupled Receptor Signaling via Radio-labeled GTP Binding

Published on: June 9, 2017

Functional domains of the mouse beta(3)-adrenoceptor associated with differential G-protein coupling

M Sato1, D S Hutchinson, B A Evans

  • 1Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia.

Biochemical Society Transactions
|October 25, 2007
PubMed

Insights

The beta(3a)-adrenoceptor (beta(3a)-AR) localizes to caveolae, restricting its G-protein signaling. Disrupting caveolae or a specific binding site alters beta(3a)-AR signaling, making it sensitive to pertussis toxin (PTX).

Area of Science:

  • Cellular Biology
  • Molecular Pharmacology
  • Biochemistry

Background:

  • G-protein-coupled receptors (GPCRs) localization in membrane microdomains influences signaling.
  • Two mouse beta(3)-adrenoceptor (beta(3)-AR) isoforms, beta(3a)-AR and beta(3b)-AR, exhibit distinct signaling properties.
  • Beta(3a)-AR is proposed to be restrained from G(i) coupling due to C-terminal interactions.

Purpose of the Study:

  • To investigate the hypothesis that beta(3a)-AR interacts with caveolin.
  • To determine the role of caveolae localization in beta(3a)-AR signaling.
  • To elucidate the mechanism by which beta(3a)-AR signaling is restricted.

Main Methods:

  • Utilized Chinese hamster ovary (CHO)-K1 cells expressing wild-type beta(3a)-ARs.
  • Employed filipin III to disrupt caveolae.
  • Mutated a putative caveolin-binding site in beta(3a)-AR.
  • Assessed cAMP accumulation sensitivity to pertussis toxin (PTX).
  • Studied endogenous beta(3a)-ARs in mouse brown adipocytes.

Main Results:

  • Disruption of caveolae or mutation of the caveolin-binding site rendered beta(3a)-AR signaling PTX-sensitive.
  • Filipin treatment of brown adipocytes reduced agonist-stimulated cAMP production, which was rescued by PTX pre-treatment.
  • These findings indicate that beta(3a)-AR localization to caveolae restricts its G(i) coupling.

Conclusions:

  • Beta(3a)-ARs are likely restricted to caveolae.
  • Receptor localization within caveolae plays a specific role in G-protein-mediated signaling.
  • Caveolin interaction is crucial for the differential signaling of beta(3a)-AR isoforms.

More Related Videos

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators07:41

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators

Published on: February 20, 2018

BRET-based G Protein Biosensors for Measuring G Protein-Coupled Receptor Activity in Live Cells09:21

BRET-based G Protein Biosensors for Measuring G Protein-Coupled Receptor Activity in Live Cells

Published on: November 7, 2025

Related Concept Videos

Adrenergic Receptors: β Subtype01:26

Adrenergic Receptors: β Subtype

β-adrenoceptors have varied sensitivities towards adrenaline, noradrenaline, and isoprenaline. The order of agonist potency is as follows:
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Adrenergic Receptors (Adrenoceptors): Classification01:27

Adrenergic Receptors (Adrenoceptors): Classification

Adrenergic receptors, or adrenoceptors, respond to the autonomic neurotransmitter noradrenaline and other endogenous catecholamine agonists. They are classified into two main families, α and β, based on their pharmacological response and are further subdivided depending on their location, elicited response, and affinity to specific agonists or antagonists.
α-Adrenoceptors
α-Adrenoceptors are classified into two main subtypes: α1 and α2. The α1 adrenoceptors, which are found on postsynaptic...
Adrenergic Receptors: ɑ Subtype01:31

Adrenergic Receptors: ɑ Subtype

Adrenoceptors are classified into α and ꞵ classes based on their potencies to catecholamine agonists. α-adrenoceptors show the following order of catecholamine potency:
Adrenaline ≥ Noradrenaline >> Isoprenaline
α-adrenoceptors are further divided into α1 and α2-adrenoceptors.
α1-Adrenoceptors: These receptors are located postsynaptically on the effector organs and cause constriction of smooth muscle mediated by activation of phospholipase C—inositol-1,4,5-trisphosphate...
Activation and Inactivation of G Proteins01:22

Activation 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...
G-protein Coupled Receptors01:21

G-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.
G-protein Coupled Receptors01:21

G-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.