Recombinant Human Olfactory receptor 2L5 (OR2L5)
Description
Classification and Nomenclature
Olfactory Receptor 2L5 (OR2L5) belongs to the G-protein coupled receptor 1 family, a major subfamily within the broader G-protein-coupled receptor (GPCR) superfamily . The nomenclature of OR2L5 has undergone several revisions in scientific literature, with alternative designations including OR2L11 and OR2L5P appearing in various databases and research publications . This nomenclature variability reflects ongoing efforts to systematically classify the extensive olfactory receptor gene family. Importantly, the nomenclature assigned to olfactory receptor genes and proteins for humans is independent of those used for other organisms, creating a species-specific identification system .
Table 1: Basic Properties of Human Olfactory Receptor 2L5 (OR2L5)
Genomic Structure
OR2L5 arises from a single coding-exon gene, a characteristic structural feature shared by most olfactory receptors in the human genome . This genomic organization distinguishes olfactory receptors from many other protein-coding genes that typically contain multiple exons separated by introns. The single-exon structure has significant evolutionary implications, potentially facilitating the rapid gene duplication and diversification events that have contributed to the remarkable expansion of this gene family across vertebrate species. The olfactory receptor gene family represents the largest gene family in the human genome, comprising approximately 400 functional genes and a similar number of pseudogenes, highlighting its biological significance in human sensory perception .
Protein Structure
The OR2L5 protein exhibits the characteristic structural features of olfactory receptors, most notably a 7-transmembrane domain architecture that is the hallmark of G-protein coupled receptors . This structure is shared with numerous neurotransmitter and hormone receptors, reflecting the common evolutionary origins and functional mechanisms of the broader GPCR superfamily. The transmembrane domains are connected by intracellular and extracellular loops that contribute to the receptor's binding specificity and signal transduction capabilities. The specific amino acid sequences within these domains determine the receptor's odor recognition profile, allowing it to interact with distinct odorant molecules with varying affinities.
Functional Domains
As a G-protein-coupled receptor, OR2L5 contains several functional domains critical for its olfactory sensory role. Knowledge regarding the specific protein domains of OR2L5 remains moderate (knowledge value: 0.41) , indicating significant gaps in our understanding of its structural determinants. The extracellular domains likely contain the odorant binding pocket, while the intracellular regions participate in G-protein coupling and downstream signal transduction. The receptor's transmembrane regions serve both structural and functional roles, maintaining the receptor's conformation while participating in the conformational changes that occur upon odorant binding and subsequent signal transduction.
Table 2: Knowledge Assessment Values for OR2L5
| Knowledge Category | Value (0 to 1 scale) |
|---|---|
| Tissue | 0.89 |
| Cell line | 0.58 |
| Protein domain | 0.41 |
| Pathway | 0.32 |
| Molecular function | 0.28 |
Note: Higher values indicate greater knowledge available in the specified category
Role in Olfactory Perception
OR2L5, like other olfactory receptors, plays a fundamental role in the initial steps of olfactory perception. These receptors interact with odorant molecules in the nasal cavity, initiating a neuronal response that ultimately triggers the perception of specific smells . The olfactory system employs a combinatorial coding strategy wherein each olfactory receptor can recognize multiple odorants, and each odorant can be detected by multiple receptors. This coding system enables humans to discriminate among thousands of different odors despite having a relatively limited number of olfactory receptor types. The specific odorant molecules that activate OR2L5 have not been comprehensively characterized, representing a significant knowledge gap in understanding the receptor's sensory function.
Signaling Mechanism
The signaling mechanism of OR2L5 follows the canonical pathway established for olfactory receptors within the GPCR family. Upon binding an odorant molecule, the receptor undergoes a conformational change that activates associated G-proteins. This activation initiates a signal transduction cascade involving second messengers, particularly cyclic adenosine monophosphate (cAMP), ultimately resulting in the generation of action potentials in olfactory sensory neurons. These signals are then transmitted to the olfactory bulb and subsequently to higher brain centers for odor perception and discrimination. Current knowledge about the specific pathway involvement of OR2L5 is relatively limited (knowledge value: 0.32) , suggesting an area requiring further investigation to fully elucidate its signaling properties and potential cross-talk with other cellular pathways.
Production Methods
Recombinant production of OR2L5 involves the expression of the human OR2L5 gene in suitable host systems to generate functional protein for research and potential therapeutic applications. While specific production methods for OR2L5 are not explicitly detailed in the available literature, general approaches for recombinant GPCR production typically involve expression in mammalian cell lines, insect cells using baculovirus expression systems, or specialized bacterial systems optimized for membrane protein expression. These expression systems must be carefully engineered to optimize protein folding, post-translational modifications, and membrane insertion to ensure functional integrity of the recombinant receptor, particularly given the complex 7-transmembrane structure of OR2L5 that presents significant challenges for proper folding and membrane integration.
Research Applications
Recombinant OR2L5 serves as a valuable tool for diverse research applications, including studies of olfactory receptor structure-function relationships, odorant specificity profiling, and investigations into non-canonical roles of olfactory receptors. Custom recombinant protein services are available for researchers interested in OR2L5, allowing for specific applications in biochemical, cellular, and physiological studies . Additionally, both monoclonal and polyclonal antibodies to OR2L5 can be generated for research purposes, enabling protein detection, localization studies, and functional characterization . These research tools facilitate investigations into the molecular mechanisms underlying olfactory perception and potential non-olfactory functions of OR2L5 in various tissues and disease states.
Table 3: Available Research Tools for OR2L5
Association with Bladder Cancer
Recent research has uncovered an intriguing potential connection between OR2L5 and primary signet ring cell carcinoma (SRCC) of the bladder, a rare and aggressive cancer type with poor prognosis. A molecular genetic analysis employing whole-exome sequencing identified OR2L5 among several driver genes potentially involved in this cancer's pathogenesis . This finding represents a novel association between an olfactory receptor and bladder carcinogenesis, expanding our understanding of the potential non-olfactory functions of these receptors. The identification of OR2L5 mutations in bladder cancer suggests that ectopic expression or altered function of this receptor may contribute to oncogenic processes in non-olfactory tissues, challenging the traditional view that olfactory receptors function exclusively in nasal sensory neurons.
Mutations and Pathogenicity
Sanger sequencing of germline DNA from a patient with primary SRCC of the bladder revealed the presence of a mutant base A/G in the OR2L5 sequence . This mutation represented the first documented association of an OR2L5 variant with this specific cancer type. The study focused on a 58-year-old male patient who presented with painless macroscopic hematuria and was subsequently diagnosed with primary SRCC of the bladder, a cancer type that demonstrates significantly worse prognosis compared to conventional urothelial carcinoma . While the functional consequences of this mutation and its precise role in bladder cancer development require further investigation, this finding suggests that altered OR2L5 function could potentially contribute to or serve as a biomarker for certain cancer subtypes, particularly the rare and aggressive SRCC of the bladder.
Table 4: OR2L5 Mutation in Primary Signet Ring Cell Carcinoma (SRCC) of the Bladder
Genetic Studies
Genetic studies involving OR2L5 have expanded beyond its role in olfaction to potential involvement in disease processes. Whole-exome sequencing research has identified OR2L5 mutations in the context of primary signet ring cell carcinoma of the bladder, revealing new dimensions to this receptor's biological significance . In the study of a patient with bladder SRCC, researchers identified 63 copy number variations (CNVs) with gain counts and 181 CNVs with loss counts . The most frequently mutated pathway was RTK-RAS, which had 85 genes involved in carcinogenic signaling . The identification of the OR2L5 mutation among several other driver genes suggests a potential role for this olfactory receptor in cancer pathogenesis, though the functional consequences of this mutation require further investigation to establish causality versus correlation in the disease process.
Product Specs
Note: We prioritize shipping the format currently in stock. However, if you have specific requirements for the format, please indicate them when placing your order, and we will accommodate your request.
Note: All our proteins are shipped with standard blue ice packs. If you require dry ice shipping, please contact us in advance, as additional fees will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. The shelf life of lyophilized form is 12 months at -20°C/-80°C.
Target Background
Q&A
What is Recombinant Human Olfactory receptor 2L5 and what is its function?
Olfactory receptor 2L5 (OR2L5) is a human odorant receptor encoded by the OR2L5 gene. It belongs to the class A family of seven-transmembrane G protein-coupled receptors (GPCRs). OR2L5 functions as an odorant receptor, interacting with odorant molecules in the nose to initiate neuronal responses that trigger smell perception . Like other olfactory receptors, OR2L5 plays a crucial role in the complex molecular machinery that allows humans to detect and distinguish between thousands of different odors. The receptor contains the canonical structure of GPCRs, featuring seven transmembrane domains and encompassing three intracellular loops along with three extracellular loops .
What are the key identifiers and synonyms for OR2L5?
OR2L5 is known by several synonyms in scientific literature and databases, which researchers should be aware of when conducting comprehensive literature searches.
Understanding these alternative identifiers is essential for comprehensive database searches and ensuring complete coverage of research literature related to this receptor.
What experimental design considerations are essential when studying OR2L5?
When designing experiments to study OR2L5, researchers must carefully consider several key variables and control parameters. Following standard experimental design principles, researchers should:
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Clearly define independent and dependent variables related to OR2L5 function or expression
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Formulate specific, testable hypotheses about OR2L5's interaction with potential ligands
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Design treatments that manipulate the independent variable (such as different odorant concentrations)
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Assign subjects to appropriate experimental groups
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Implement rigorous measurements of the dependent variable (such as receptor activation)
| Extraneous Variable | Control Method |
|---|---|
| Temperature variations | Maintain consistent temperature during all assays |
| Cell line differences | Use standardized cell lines for expression studies |
| Contamination | Implement strict sterility protocols |
| Reagent variability | Use single lots of critical reagents when possible |
| Time-dependent effects | Standardize all timing aspects of experiments |
Additionally, researchers should consider using a positive control (a known olfactory receptor-ligand pair) alongside OR2L5 experiments to validate experimental conditions .
What structural analysis methods are most suitable for studying OR2L5?
Given the challenges in experimentally determining the structure of olfactory receptors, researchers should consider a multi-method approach to study OR2L5's structure:
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Computational Prediction: AlphaFold2 can be used to predict the three-dimensional structure of OR2L5 with reasonable accuracy, providing initial structural insights. These predictions can serve as starting points for further analysis .
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Cryo-Electron Microscopy (Cryo-EM): While challenging for membrane proteins like ORs, cryo-EM has successfully been used to resolve structures of some olfactory receptors. This technique could potentially reveal the structural details of OR2L5, particularly when the receptor is in complex with a ligand or G protein .
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Molecular Dynamics Simulations: These simulations can model the behavior of OR2L5 in a lipid bilayer environment, providing insights into conformational changes upon ligand binding. This is particularly valuable when experimental structures are not available .
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Site-Directed Mutagenesis: Systematic mutation of key residues predicted to be involved in ligand binding, followed by functional assays, can validate computational predictions and reveal crucial binding pocket residues .
The integration of these methods offers the most comprehensive approach to understanding OR2L5's structure and function relationship.
How can molecular dynamics simulations be optimally applied to OR2L5 research?
Molecular dynamics (MD) simulations represent a powerful tool for investigating OR2L5's binding mechanisms and conformational dynamics. For optimal application:
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System Preparation: Start with the AlphaFold2-predicted structure of OR2L5, embedded in a lipid bilayer that mimics the olfactory epithelium membrane composition. The system should include explicit water molecules and appropriate ion concentrations .
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Binding Site Identification: Use binding site prediction algorithms and comparative analysis with related olfactory receptors to identify potential ligand binding pockets within OR2L5.
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Docking Studies: Perform molecular docking of potential odorant molecules to the identified binding sites to generate initial bound conformations .
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Simulation Parameters: Run multiple MD simulations (typically 100-500 ns each) with different starting conditions to ensure adequate sampling of conformational space. Temperature and pressure should be maintained at physiological conditions (310K, 1 atm) .
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Analysis Metrics: Key analyses should include:
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Validation: Computational predictions should be validated through experimental approaches such as site-directed mutagenesis of key predicted binding residues followed by functional assays .
These simulations can reveal dynamic events that are difficult to capture experimentally, such as ligand entry pathways, transient interactions, and conformational changes associated with receptor activation.
What approaches can be used to identify potential ligands for OR2L5?
Identifying ligands for orphan olfactory receptors like OR2L5 requires a systematic approach combining computational and experimental methods:
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Sequence-Based Predictions: Analyze the binding pocket sequence of OR2L5 in comparison with olfactory receptors with known ligands. Receptors with similar binding pocket residues may recognize similar odorants .
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Protein Chemistry Metric Models: Implement machine learning approaches similar to the Protein Chemistry Metric (PCM) model developed by Jérôme Golebiowski's team. This model uses OR sequence similarity and physicochemical characteristics of ligands to predict potential OR-odorant pairs. Such models have achieved hit rates of approximately 58% in identifying novel odorant-OR pairs .
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Virtual Screening: Conduct large-scale virtual screening of odorant databases against the predicted binding pocket of OR2L5. This can be done using molecular docking software such as AutoDock Vina, Glide, or GOLD.
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Pharmacophore Modeling: Develop pharmacophore models based on known olfactory receptor-ligand interactions and use these to screen for potential OR2L5 ligands.
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Experimental Validation: The most promising candidates from computational predictions should be tested experimentally using:
This integrated approach maximizes the likelihood of successfully identifying ligands for this understudied receptor.
What are the main challenges in expressing and purifying recombinant OR2L5 for structural studies?
Expressing and purifying functional olfactory receptors like OR2L5 presents several significant challenges:
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Low Expression Levels: Olfactory receptors typically express poorly in heterologous systems due to misfolding and aggregation.
Solution: Use specialized expression systems such as inducible mammalian cell lines with chaperone co-expression or insect cell expression systems (Sf9, Hi5) that may better accommodate GPCR folding. Additionally, fusion partners like T4 lysozyme or BRIL can enhance expression and stability.
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Membrane Protein Instability: As a seven-transmembrane protein, OR2L5 requires a lipid environment for stability.
Solution: Utilize detergent screening to identify optimal solubilization conditions. Nanodiscs, lipid cubic phase, or styrene maleic acid lipid particles (SMALPs) can provide more native-like environments for purified receptors.
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Conformational Heterogeneity: GPCRs like OR2L5 exist in multiple conformational states, complicating structural studies.
Solution: Employ conformational stabilization techniques such as thermostabilizing mutations, antibody fragments, or nanobodies that lock the receptor in specific conformations.
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Low Purification Yields: The multi-step purification process often results in significant loss of functional protein.
Solution: Optimize each purification step with small-scale trials before scaling up. Consider affinity tags like FLAG, His10, or tandem tags to improve purification efficiency while minimizing the impact on protein function.
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Ligand Dependency: Without known ligands, stabilizing OR2L5 in an active conformation for structural studies is challenging.
Solution: Use computational approaches to identify potential stabilizing ligands or focus initially on capturing the apo (unbound) state structure.
These solutions require iterative optimization for each specific olfactory receptor, as the optimal conditions may vary significantly between different OR family members.
How can researchers validate the functionality of recombinant OR2L5?
Validating the functionality of recombinantly expressed OR2L5 is crucial to ensure that research findings are physiologically relevant. Comprehensive validation should include:
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Localization Studies: Confirm proper membrane localization using:
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Immunofluorescence microscopy with OR2L5-specific antibodies
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GFP/YFP fusion constructs to visualize cellular localization
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Cell surface biotinylation assays to quantify membrane expression
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Ligand Binding Assays: While no specific ligands are currently known for OR2L5, researchers can:
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Perform competitive binding assays with structurally diverse odorants
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Use photoaffinity labeling with promiscuous odorant analogues
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Employ microscale thermophoresis or surface plasmon resonance with candidate ligands
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Functional Response Assays: Measure receptor activation using:
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Structural Integrity Assessment: Evaluate the correct folding of the recombinant protein through:
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Circular dichroism spectroscopy to assess secondary structure
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Limited proteolysis patterns compared to other GPCRs
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Thermostability assays to measure protein stability
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Cross-Validation: Compare results across different expression systems:
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HEK293 cells
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Sf9 insect cells
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Yeast expression systems
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Cell-free expression systems
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Proper validation ensures that subsequent research on OR2L5 binding mechanisms and structure-function relationships is based on physiologically relevant receptor conformations.
What statistical approaches are most appropriate for analyzing OR2L5 binding data?
When analyzing binding data for OR2L5, researchers should implement rigorous statistical approaches tailored to the specific experimental design:
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Dose-Response Analysis: For ligand screening and characterization:
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Fit data to appropriate models (Hill equation, four-parameter logistic model)
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Calculate EC50/IC50 values with 95% confidence intervals
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Compare potency across different ligands using extra sum-of-squares F test
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Mutation Studies Analysis: For structure-function research:
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Use two-way ANOVA to assess the effects of mutations and ligands
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Apply Bonferroni or Tukey's post-hoc tests for multiple comparisons
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Calculate fold-changes in potency or efficacy with propagated errors
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Binding Kinetics Analysis: For association/dissociation studies:
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Fit to appropriate kinetic models (one-phase, two-phase)
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Calculate kon and koff rates with associated errors
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Derive dissociation constants (KD) from kinetic parameters
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Molecular Dynamics Data Analysis:
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Machine Learning Model Validation:
For all analyses, researchers should report effect sizes alongside p-values and clearly state the statistical power of their experiments. Given the preliminary nature of OR2L5 research, Bayesian approaches may be particularly valuable for incorporating prior knowledge and updating models as new data becomes available.
How can researchers address contradictory findings in OR2L5 studies?
Given the limited knowledge about OR2L5 and the technical challenges in olfactory receptor research, contradictory findings may emerge. Researchers should address these systematically:
By systematically addressing contradictions, researchers can advance the field's understanding of OR2L5 and potentially uncover previously unrecognized complexities in olfactory receptor function.
What emerging technologies might accelerate OR2L5 research?
Several cutting-edge technologies have the potential to significantly advance OR2L5 research:
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Cryo-EM Advances: Recent developments in cryo-EM techniques, including improved detectors and processing algorithms, may enable structure determination of challenging membrane proteins like OR2L5 at higher resolutions. These advances could reveal critical structural details that have remained elusive .
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AlphaFold2 and Deep Learning: The continued evolution of protein structure prediction tools like AlphaFold2, particularly when combined with experimental data, may provide increasingly accurate models of OR2L5 structure and dynamics. This could facilitate more precise virtual screening and binding site predictions .
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Artificial Intelligence for Ligand Discovery: AI-driven approaches that integrate chemical, biological, and structural data can accelerate the identification of potential OR2L5 ligands. These methods could analyze patterns across the olfactory receptor family to make predictions specific to OR2L5 .
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Single-Cell Techniques: Advanced single-cell RNA sequencing and proteomics can provide insights into the expression patterns and co-regulatory networks of OR2L5 in olfactory neurons, potentially revealing physiological contexts critical for understanding its function.
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Organoid Models: Olfactory epithelium organoids could provide more physiologically relevant systems for studying OR2L5 function within its native cellular environment, enabling investigations of receptor trafficking, localization, and signaling.
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CRISPR-Based Technologies: Gene editing approaches can facilitate:
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Creation of reporter systems for endogenous OR2L5 expression
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Generation of knock-in models for studying OR2L5 function in vivo
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High-throughput mutagenesis to comprehensively map structure-function relationships
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Mass Photometry and Other Biophysical Techniques: Emerging biophysical methods may enable direct measurement of OR2L5-ligand interactions and oligomerization states under near-native conditions.
Integration of these technologies into OR2L5 research programs could substantially accelerate progress in understanding this understudied olfactory receptor.
