Voltage Dependence of Prostanoid Receptors

Area of Science:

• Cellular and Molecular Biology
• Neuroscience
• Pharmacology

Background:

• G protein-coupled receptors (GPCRs) are crucial transmembrane signal transducers.
• GPCRs are exposed to the plasma membrane's electrical field, suggesting potential voltage sensitivity.
• Previous studies indicated voltage modulation of ligand-induced GPCR activity in select receptors.

Purpose of the Study:

• To investigate the voltage dependence of the thromboxane receptor (TP receptor) and its downstream signaling.
• To identify the molecular mechanisms underlying voltage modulation of TP receptor activity.
• To explore voltage sensitivity in other prostanoid receptors.

Main Methods:

• Utilized Förster resonance energy transfer (FRET)-based biosensors in patch clamp experiments.
• Performed site-directed mutagenesis to identify key residues involved in voltage sensitivity.
• Assessed receptor activity and downstream signaling under varying membrane potentials.

Main Results:

• TP receptor activity robustly depended on membrane voltage, doubling upon depolarization.
• Depolarization affected agonist affinity and modulated the general conformation of the TP receptor.
• Mutation of residue R295^7.40 altered the TP receptor's voltage sensitivity.
• Prostaglandin F and E₂ receptors showed voltage sensitivity, while prostacyclin receptors did not.

Conclusions:

• Membrane depolarization significantly modulates the activity of TP receptors, prostaglandin F receptors, and prostaglandin E₂ receptors.
• Voltage-induced conformational changes in the TP receptor are mediated by specific residues like R295^7.40.
• Voltage dependence is a relevant factor in the physiological function of certain prostanoid receptors in excitable cells.