OR8D1 (Olfactory Receptor Family 8 Subfamily D Member 1) is a member of the olfactory receptor family, which constitutes the largest gene family in the mammalian genome. The protein is primarily known for its role in olfactory signal transduction and is classified as a G-protein-coupled receptor (GPCR) . OR8D1 is also known by several synonyms including Olfactory receptor 8D3, Olfactory receptor OR11-301, Olfactory receptor-like protein JCG9, OR8D3, and OST004 . The human OR8D1 protein has a molecular weight of approximately 34 kDa and is encoded by a gene located on chromosome 11 .
Olfactory receptors like OR8D1 interact with odorant molecules to initiate neuronal responses that trigger smell perception. These receptors share a characteristic 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals .
OR8D1, like other olfactory receptors, features a 7-transmembrane domain structure characteristic of G-protein-coupled receptors. The protein contains intracellular and extracellular domains that facilitate signal transduction following odorant binding . The human OR8D1 protein sequence is available in protein databases under UniProt accession number Q8WZ84 .
Interestingly, OR8D1 has been detected in human spermatozoa at both mRNA and protein levels, suggesting a potential role in sperm function . Studies have shown that various OR ligands can induce calcium (Ca²⁺) signals in human spermatozoa, which can be inhibited by mibefradil. This indicates that olfactory receptors may play important roles in sperm chemotaxis and chemokinesis, crucial processes for mammalian reproduction .
OR8D1 antibodies available commercially are predominantly rabbit polyclonal antibodies produced using synthetic peptides derived from human OR8D1 sequences. Most manufacturers use peptides from the C-terminal region of the protein as immunogens . The antibodies are typically purified from rabbit antiserum using affinity chromatography with the immunizing peptide to ensure specificity .
Commercial OR8D1 antibodies undergo validation for various applications including Western Blot (WB), Immunofluorescence (IF), and Enzyme-Linked Immunosorbent Assay (ELISA). Validation data typically include demonstration of specificity against human OR8D1 and determination of optimal working dilutions for different applications .
The following table summarizes the validation characteristics of commercially available OR8D1 antibodies:
| Validation Parameter | Details |
|---|---|
| Target Species | Primarily Human |
| Validated Applications | Western Blot, Immunofluorescence, ELISA |
| Recommended Dilutions | WB: 1:500-1:1000, IF: 1:100-1:500, ELISA: 1:20000 |
| Cross-Reactivity | Minimal with other proteins |
| Antibody Format | Primarily unconjugated |
| Isotype | IgG |
OR8D1 antibodies are typically supplied as liquid formulations in buffered solutions containing stabilizers and preservatives. Common formulation components include :
Phosphate Buffered Saline (PBS), pH 7.4
Glycerol (often 50%)
Sodium azide (0.02%) as a preservative
Bovine Serum Albumin (BSA) (0.5% in some formulations)
The products are generally shipped on wet ice and should be stored at -20°C, with manufacturers recommending avoiding repeated freeze-thaw cycles to maintain antibody activity .
OR8D1 antibodies have been validated for western blot applications, allowing researchers to detect and quantify OR8D1 protein expression in various tissues and cell lines. The recommended dilution range for western blot applications is typically 1:500-1:1000 . Western blot analysis reveals OR8D1 as a protein with a molecular weight of approximately 34 kDa .
OR8D1 antibodies can be used for immunofluorescence (IF) and immunocytochemistry (ICC) at dilutions typically ranging from 1:100 to 1:500 . These applications allow researchers to visualize the subcellular localization of OR8D1 in cells and tissues, providing insights into its distribution patterns and potential functional significance.
Enzyme-Linked Immunosorbent Assay (ELISA) applications of OR8D1 antibodies typically employ higher dilutions, often around 1:20000 . This application enables quantitative detection of OR8D1 in complex biological samples.
Some OR8D1 antibodies, such as Sigma-Aldrich's HPA059510, have been specifically validated for immunohistochemistry applications . These can be used at dilutions of 1:200-1:500 to study OR8D1 distribution in tissue sections.
A comprehensive analysis of olfactory receptor transcripts in human spermatozoa revealed that OR8D1 is among the 91 different OR transcripts detected in human sperm samples. This study, published in Frontiers in Molecular Biosciences, was the first to provide a comprehensive analysis of OR transcripts in human spermatozoa from several individuals using RNA-Seq technology .
The detection of OR proteins in various compartments of human spermatozoa suggests distinct functions in human sperm. Notably, a panel of various OR ligands induced Ca²⁺ signals in human spermatozoa, which could be inhibited by mibefradil, indicating a potential role for these receptors in sperm function and fertilization processes .
Research published in PLOS Genetics examined the functional evolution of mammalian odorant receptors, including OR8D1. The study found that human OR8D1 is "hyperfunctional" compared to chimpanzee and macaque OR8D1 orthologs, while human paralogs OR8D2 and OR8D4 do not respond to the same ligands .
Interestingly, while OR orthologs tend to show conserved ligand selectivity (responding to a common ligand 82% of the time), they exhibit dynamic changes in potency and/or efficacy during evolution, even in closely related species. In contrast, human OR paralogs of the same subfamily responded to common ligands only 33% of the time .
The study discovered that 87% of human-primate orthologs and 94% of mouse-rat orthologs showed differences in receptor potency (EC50) and/or efficacy (dynamic range) to individual ligands. Notably, the dN/dS ratio, which indicates selective pressure during evolution, does not predict functional similarities between orthologs .
Research on OR8D1 and related olfactory receptors continues to expand beyond traditional olfactory functions. The detection of OR8D1 in human spermatozoa suggests potential roles in reproduction that warrant further investigation. Future studies may explore:
The specific ligands that activate OR8D1 in different cellular contexts
The signaling pathways downstream of OR8D1 activation
The potential role of OR8D1 in sperm chemotaxis and fertilization
Comparative studies of OR8D1 function across species to understand evolutionary adaptations
Potential applications of OR8D1 antibodies in diagnostic or therapeutic contexts
Research tools like OR8D1 antibodies will remain essential for advancing our understanding of this receptor's biology and function in various physiological contexts.
OR8D1 (Olfactory Receptor Family 8 Subfamily D Member 1) functions as an odorant receptor and may be involved in taste perception. It belongs to the G-protein coupled receptor 1 family and is primarily expressed in the tongue . Like other olfactory receptors, OR8D1 interacts with odorant molecules to initiate neuronal responses that trigger the perception of smell. The protein is located in the cell membrane as a multi-pass membrane protein with a molecular weight of approximately 34 kDa . Understanding this receptor's function is essential for designing experiments that investigate sensory perception mechanisms.
Currently available OR8D1 antibodies include both polyclonal and monoclonal varieties derived from rabbit or mouse hosts. Polyclonal antibodies are commonly developed against the C-terminal region of human OR8D1, specifically targeting amino acids in the ranges of 224-273, 234-283, or 235-284 . These antibodies are typically unconjugated but can be used with appropriate secondary antibodies for detection. The selection between polyclonal and monoclonal antibodies should be based on your specific experimental requirements, with polyclonals offering broader epitope recognition and monoclonals providing higher specificity.
OR8D1 antibodies have been validated for several standard immunological techniques:
Western Blotting (WB): For detecting denatured OR8D1 protein in cell or tissue lysates
Enzyme-Linked Immunosorbent Assay (ELISA): For quantitative detection in solution
Immunofluorescence (IF): For visualizing cellular localization of OR8D1
When designing your experiment, consider that validation data is typically available from manufacturers showing detection of OR8D1 in human cell lines such as Jurkat, HepG, and MCF-7 .
Optimal dilutions vary by application and specific antibody product:
| Application | Recommended Dilution Range | Notes |
|---|---|---|
| Western Blotting | 1:500-1:2000 | Lower dilutions may increase signal strength but could increase background |
| Immunofluorescence | 1:100-1:1000 | Start with 1:200 for polyclonal antibodies |
| ELISA | 1:20000 | Higher dilution reflects high sensitivity in this format |
Always perform a dilution series in your specific experimental system to determine optimal conditions, as factors like expression levels and sample preparation methods can affect antibody performance .
For effective Western blot detection of OR8D1:
Use fresh tissue or cell samples with protease inhibitors to prevent degradation
For membrane proteins like OR8D1, include proper membrane solubilization steps using detergents such as RIPA buffer
Maintain samples at appropriate temperatures (4°C during preparation, -20°C or below for storage)
Include denaturants like SDS and reducing agents like β-mercaptoethanol to effectively expose epitopes
Since OR8D1 has a molecular weight of 34 kDa, use 10-12% polyacrylamide gels for optimal resolution
For transfer, PVDF membranes are recommended for this membrane protein
When probing, follow the manufacturer's recommended dilutions and include proper blocking to reduce nonspecific binding .
To preserve antibody activity and prevent degradation:
Store antibodies at -20°C or -80°C for long-term storage
Avoid repeated freeze-thaw cycles that can degrade antibody structure
For working stocks, small aliquots can be prepared and stored at 4°C for short periods
Most OR8D1 antibodies are supplied in a stabilizing buffer containing 50% glycerol, 0.5% BSA, and 0.02% sodium azide
Prior to use, allow the antibody to equilibrate to room temperature and mix gently
When shipping or temporarily storing antibodies, maintaining a cold chain (4°C) is sufficient for short periods .
Comprehensive validation requires multiple approaches:
Positive and negative controls: Use tissues/cells known to express OR8D1 (tongue epithelium) and those lacking expression
Peptide competition assay: Pre-incubate the antibody with its immunizing peptide (C-terminal peptide of human OR8D1) to confirm signal specificity
siRNA knockdown: Reduce OR8D1 expression in a relevant cell line and confirm corresponding reduction in antibody signal
Recombinant expression: Overexpress tagged OR8D1 and confirm co-localization of tag and antibody signals
Multiple antibody comparison: Use different antibodies targeting distinct epitopes of OR8D1 and compare detection patterns
For OR8D1 specifically, validation in tongue tissue samples would be particularly relevant given its known expression pattern .
Cross-reactivity is a significant concern when working with olfactory receptors due to sequence homology:
Review sequence alignment: Compare the immunogen sequence (amino acids 234-283) with other olfactory receptors to identify potential cross-reactivity
Species-specific considerations: While most OR8D1 antibodies are developed against human sequences, cross-reactivity with rat and mouse OR8D1 has been reported
Absorption controls: Include lysates from cells expressing related receptors but not OR8D1
Western blot analysis: Evaluate band patterns to identify potential cross-reactivity (a single 34 kDa band suggests specificity)
Blocking peptides: Use specific peptides from related receptors to identify potential cross-reactivity
When interpreting results, consider that polyclonal antibodies may show broader cross-reactivity than monoclonal options .
Deep learning methods offer complementary approaches to antibody-based studies:
Structure prediction: Tools like ABodyBuilder2 can predict antibody structures from sequence data, providing insights into epitope-parabody interactions
Epitope mapping: Deep learning can predict which regions of OR8D1 are likely recognized by specific antibodies
Conformation analysis: For membrane proteins like OR8D1, structural prediction can reveal likely conformational states that antibodies might preferentially recognize
Cross-reactivity prediction: Computational methods can identify potential cross-reactivity with other proteins
Integrative approach: Combine experimental antibody data with predicted structures for more comprehensive understanding
Recent research shows that while deep learning models excel at recognizing canonical structure forms, they may not accurately predict completely novel conformations not represented in training data .
When troubleshooting Western blots with OR8D1 antibodies:
| Issue | Potential Causes | Solutions |
|---|---|---|
| No signal | Low expression, degradation, improper sample preparation | Use enriched membrane fractions, add protease inhibitors, optimize lysis conditions for membrane proteins |
| Multiple bands | Cross-reactivity, protein degradation, post-translational modifications | Use more stringent washing, try monoclonal antibodies, include phosphatase inhibitors |
| High background | Insufficient blocking, excessive antibody concentration | Increase blocking time, optimize antibody dilution, use alternative blocking agents |
| Incorrect molecular weight | Post-translational modifications, alternative splicing | Compare with positive control lysates, consider deglycosylation treatment |
For membrane proteins like OR8D1, heating samples to 70°C instead of boiling can help prevent aggregation that may occur with complete denaturation .
For successful IF experiments with OR8D1:
Fixation method: Compare paraformaldehyde and methanol fixation to determine which better preserves the OR8D1 epitope
Permeabilization optimization: For this membrane protein, gentle detergents like 0.1% Triton X-100 are recommended
Antigen retrieval: Consider mild antigen retrieval methods if initial results show weak signal
Signal amplification: For low expression systems, consider tyramide signal amplification or higher sensitivity detection systems
Background reduction: Extended washing steps and careful titration of primary antibody (starting at 1:200 dilution)
Co-localization studies: Pair with markers of cellular compartments to confirm membrane localization
For tongue tissue sections, include taste bud markers to correlate OR8D1 localization with functional taste cell populations .
When facing reproducibility challenges:
Document all experimental conditions meticulously, as membrane protein detection can be particularly sensitive to subtle protocol variations .
OR8D1's expression in the tongue suggests important roles in taste perception that can be investigated using antibodies:
Cell type identification: Use OR8D1 antibodies in combination with established taste cell markers to identify specific subpopulations
Receptor trafficking studies: Track OR8D1 localization under different taste stimuli conditions
Signal transduction research: Combine OR8D1 detection with phospho-specific antibodies to map activation pathways
Developmental studies: Examine OR8D1 expression during taste bud development and regeneration
Comparative physiology: Analyze OR8D1 distribution across species to understand evolutionary adaptations in taste perception
These approaches can help elucidate how olfactory receptors contribute to taste perception beyond their traditional roles in olfaction .
Several cutting-edge techniques can be integrated with OR8D1 antibody applications:
Proximity ligation assays: Detect protein-protein interactions involving OR8D1 with high sensitivity
Super-resolution microscopy: Visualize OR8D1 distribution within membrane microdomains
Single-cell proteomics: Combine with antibody-based detection to correlate OR8D1 expression with cellular phenotypes
Mass cytometry (CyTOF): Multiplex OR8D1 detection with dozens of other markers for comprehensive cellular profiling
CRISPR-based tagging: Generate endogenously tagged OR8D1 to correlate with antibody detection and validate specificity
These methods can significantly extend the utility of OR8D1 antibodies beyond traditional applications, providing deeper insights into receptor function and regulation .
Integrating computational methods with OR8D1 antibody research offers several advantages:
Epitope prediction: Computational tools can identify optimal epitopes for generating new OR8D1 antibodies with improved specificity
Structure-function relationships: Deep learning models can predict how OR8D1 structure affects antibody binding and function
Cross-reactivity prediction: Algorithms can assess potential cross-reactivity with other olfactory receptors before experimental testing
Canonical form analysis: Deep learning approaches like those used in ABodyBuilder2 can analyze structural patterns in antibody-antigen interactions
Integrative data analysis: Combine antibody-based experimental data with computational predictions to generate more robust hypotheses
While computational methods show promise, recent research indicates they work best when complementing experimental approaches rather than replacing them, as they may not accurately predict completely novel conformations .