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Related Concept Videos

Channel Rhodopsins01:11

Channel Rhodopsins

Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
G-Protein Gated Ion Channels01:21

G-Protein Gated Ion Channels

GPCRs are primarily responsible for our sense of smell, taste, and vision.  The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory organs,...
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...
Photoreceptors and Visual Pathways01:22

Photoreceptors and Visual Pathways

At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
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 Receptors01:15

G 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...

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Related Experiment Video

Updated: May 21, 2026

Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization
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Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization

Published on: March 16, 2020

Molecular Properties of a Novel Inward Proton Pump Rhodopsin, GhXeR.

Nanako Hattori1, Yuma Ito1, Yuji Furutani1,2

  • 1Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.

The Journal of Physical Chemistry. B
|May 19, 2026
PubMed
Summary

This study reveals that Guptibacillus hwajinpoensis xenorhodopsin (GhXeR) functions as an inward proton pump. GhXeR shows potential as a superior optogenetic tool due to its prolonged activity.

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A Rhodopsin Transport Assay by High-Content Imaging Analysis
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Last Updated: May 21, 2026

Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization
09:19

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Published on: March 16, 2020

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
10:03

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy

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A Rhodopsin Transport Assay by High-Content Imaging Analysis
12:11

A Rhodopsin Transport Assay by High-Content Imaging Analysis

Published on: January 16, 2019

Area of Science:

  • Microbiology
  • Biophysics
  • Optogenetics

Background:

  • Microbial rhodopsins exhibit diverse proton pump functions, including outward and inward proton transport driven by light.
  • The physiological significance of light-driven inward proton pumps remains largely unexplored.

Purpose of the Study:

  • Investigate the molecular properties of xenorhodopsin (XeR) from Guptibacillus hwajinpoensis (GhXeR).
  • Evaluate GhXeR as a potential optogenetic tool compared to existing options like NsXeR.
  • Elucidate the molecular mechanisms underlying GhXeR's proton pumping activity.

Main Methods:

  • Heterologous expression of GhXeR in E. coli.
  • Spectroscopic analysis including low-temperature UV-visible and FTIR spectroscopy.
  • Assessment of proton pump activity and solvent pH changes.

Main Results:

  • GhXeR functions as an inward proton pump in heterologous expression systems.
  • GhXeR exhibits comparable proton pump activity to NsXeR but for a significantly longer duration.
  • Spectroscopic data indicate retinal photoisomerization and chromophore distortion store light energy.

Conclusions:

  • GhXeR is a promising optogenetic tool with enhanced duration of action.
  • The study provides insights into the molecular mechanism of inward proton pumping.
  • GhXeR offers a unique system for studying the physiological roles of inward proton pumps.