Related Experiment Video
Updated: Jun 19, 2026
08:38
Transretinal ERG Recordings from Mouse Retina: Rod and Cone Photoresponses
Published on: March 14, 2012
Functional interchangeability of rod and cone transducin alpha-subunits
Wen-Tao Deng1, Keisuke Sakurai, Jianwen Liu
1Department of Ophthalmology, University of Florida, Gainesville, FL 32610, USA. wdeng@ufl.edu
Summary
Rod and cone transducin alpha-subunits (Talpha) are functionally interchangeable, despite structural differences. Their signaling properties do not explain the distinct light sensitivities of rods and cones.
Area of Science:
- Vision science
- Molecular biology
- Phototransduction
Background:
- Rods and cones have distinct phototransduction proteins for dim and bright light vision.
- Rod and cone visual pigments couple to different transducin variants.
- The functional impact of structural differences in rod and cone transducin alpha subunits (Talpha) is unknown.
Purpose of the Study:
- To investigate the role of structural differences between rod and cone Talpha in photoreceptor function.
- To determine if rod Talpha functions in cones and cone Talpha functions in rods.
- To assess the contribution of Talpha variants to the functional differences between rods and cones.
Main Methods:
- Studied Talpha translocation and signaling in knockout and mutant mouse models.
- Expressed rod Talpha in cones and cone Talpha in rods.
- Utilized electroretinogram (ERG) responses and single-cell recordings for functional analysis.
Main Results:
- Exogenously expressed rod or cone Talpha localized and translocated identically to endogenous Talpha.
- Expressed Talpha variants rescued ERG responses in respective knockout mice.
- Rod and cone Talpha demonstrated comparable rod sensitivity and response kinetics in rescue experiments.
Conclusions:
- Rod and cone Talpha are functionally interchangeable in photoreceptor signaling.
- Structural differences between rod and cone Talpha do not account for their distinct light sensitivities.
- The methodology enables functional analysis of homologous protein swaps in different cell types.
Related Concept Videos
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...
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...
01:32The Retina
The retina is a layer of nervous tissue at the back of the eye that transduces light into neural signals. This process, called phototransduction, is carried out by rod and cone photoreceptor cells in the back of the retina.
01:58Cooperative Allosteric Transitions
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
01:57Protein Complexes with Interchangeable Parts
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
01:11Channel 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,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...