OR4C13 Antibody

What is OR4C13 and why is it significant for research?

OR4C13 (Olfactory Receptor Family 4 Subfamily C Member 13) is a protein that in humans is encoded by the OR4C13 gene. It belongs to the largest gene family in the human genome - the olfactory receptor family. OR4C13 is a 309 amino acid multi-pass membrane protein that functions as a G-protein-coupled receptor (GPCR) .

Olfactory receptors interact with odorant molecules in the nose to initiate neuronal responses that trigger smell perception. These receptors share a 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals .

Research significance:

• OR4C13 has been detected in reproductive tissues, suggesting roles beyond olfaction

• Expression changes have been observed in traumatic brain injury

• Genetic variants have been implicated in chronic cough

• Studies of OR4C13 contribute to understanding GPCR signaling mechanisms

Studies have revealed that OR4C13 expression extends beyond the olfactory epithelium:

• Reproductive system: OR4C13 has been detected in:

  • Seminal plasma via Western blot

  • Sperm cells, localized to the acrosome, midpiece, and flagellum

  • Testicular tissue, with expression in spermatogonia, spermatocytes, and spermatids

  • Epididymis, showing intense and diffuse staining in the pseudostratified columnar epithelium

• Neurological tissues: OR4C13 expression has been investigated in:

  • Neuronally derived extracellular vesicles from serum samples of traumatic brain injury patients

This diverse expression pattern suggests that OR4C13 may have physiological functions beyond olfaction, particularly in reproductive biology.

How should I validate the specificity of an OR4C13 antibody for my research?

Validating antibody specificity is crucial for reliable research outcomes. For OR4C13 antibodies, consider the following validation approaches:

• Positive and negative controls:

  • Use tissues with known OR4C13 expression (e.g., testicular tissue) as positive controls

  • Use tissues where OR4C13 is not expressed or use OR4C13 knockout/knockdown models as negative controls

• Gene silencing validation:

  • Use OR4C13 shRNA lentiviral particles (e.g., sc-96386-V) to knock down OR4C13 expression

  • Compare antibody staining between knockdown and control samples

• Peptide competition assay:

  • Pre-incubate the antibody with the immunizing peptide before application

  • Specific staining should be blocked by the peptide

• Multiple antibody validation:

  • Compare staining patterns using antibodies targeting different epitopes of OR4C13

  • Consistent patterns across different antibodies suggest specificity

• Western blot analysis:

  • Confirm a single band of the expected molecular weight (~34 kDa)

  • Absence of non-specific bands

What protocol is recommended for OR4C13 detection in reproductive tissues?

Based on published research, the following protocol has been successful for detecting OR4C13 in reproductive tissues :

Immunofluorescence staining of testicular sections:

• Fix tissue sections in 2% paraformaldehyde for 20 minutes at room temperature

• Embed in paraffin and section

• Deparaffinize sections

• Perform antigen retrieval

• Block with 5% BSA for 1 hour

• Incubate with anti-OR4C13 antibody (1:100 dilution) overnight at 4°C

• Wash three times with PBS

• Incubate with FITC-conjugated secondary antibody

• For sperm cells, co-stain with Lectin-PNA Alexa Fluor 594-Conjugate (1:100) to visualize acrosomes

• Counterstain nuclei with DAPI or TOPRO3

• Visualize using confocal microscopy

Western blot of seminal plasma:

• Treat samples with Reducing Laemmli buffer (31.5 mM Tris–HCl pH 6.8, 1% SDS, 10% glycerol, 0.005% bromophenol blue with 355 mM 2-mercaptoethanol)

• Boil at 95°C for 5 minutes

• Separate proteins by SDS-PAGE

• Transfer onto PVDF membrane

• Block with appropriate blocking buffer

• Incubate with anti-OR4C13 antibody (1:500 dilution)

• Wash and incubate with appropriate secondary antibody

• Develop using enhanced chemiluminescence (ECL)

How can OR4C13 antibodies be used to investigate fertility-related research?

OR4C13 antibodies have enabled significant discoveries in reproductive biology research. Here are methodological approaches for fertility studies:

• Expression pattern analysis in male reproductive tract:

  • Immunohistochemistry of different regions of the male reproductive tract has revealed that OR4C13 is expressed in testicular spermatocytes, spermatids, and throughout the epididymis

  • Differential expression patterns between fertile individuals and those with fertility issues (e.g., secretive azoospermia with spermatocyte maturation arrest) have been observed

• Functional studies in sperm:

  • OR4C13 localization to the acrosome, midpiece, and flagellum of sperm suggests potential roles in sperm function

  • Similar to other olfactory receptors (e.g., OR17-4), OR4C13 may be involved in:

    • Sperm chemotaxis

    • Acrosome reaction

    • Sperm motility activation

• Comparative analysis in fertility disorders:

  • In azoospermic patients with spermatocyte maturative arrest, OR4C13 showed weak positivity only in spermatogonia, compared to expression throughout the tubules in normal testicular tissue

  • This differential expression pattern may serve as a biomarker for specific fertility disorders

• Proteomic approaches:

  • OR4C13 was identified in seminal plasma through high-resolution mass spectrometry

  • This "protein-target" approach can be used to identify the wider OR repertoire in reproductive samples

What are the emerging findings about OR4C13 in neurological research?

Recent studies have implicated OR4C13 in neurological conditions, particularly traumatic brain injury (TBI) and chronic cough, opening new research avenues:

• OR4C13 in traumatic brain injury:

  • Expression analysis of OR4C13 in neuronally derived extracellular vesicles (EVs) from serum samples showed significant differences between TBI patients and controls

  • Both severe TBI (sTBI) and mild TBI (mTBI) showed altered OR4C13 expression compared to non-TBI controls (p = 0.0053 and p < 0.001, respectively)

  • Methodology: Researchers evaluated OR4C13 expression in neuronally derived EVs isolated from serum

• OR4C13 in chronic cough research:

  • Recent genomic studies of chronic cough identified OR4C13 as one of the novel genes involved in neurological processes associated with cough

  • This finding suggests a potential role for olfactory receptors in cough hypersensitivity and neuronal dysfunction mechanisms

These emerging applications highlight the importance of OR4C13 beyond olfaction and reproductive biology, suggesting broader neurological functions that merit further investigation.

What technical challenges exist when studying OR4C13 and how can they be addressed?

Researchers face several technical challenges when studying OR4C13:

• Antibody cross-reactivity with other olfactory receptors:

  • The olfactory receptor family is large with many similar proteins

  • Solution: Validate antibody specificity using multiple approaches, including peptide competition assays and genetic knockdown models

• Low expression levels in certain tissues:

  • OR4C13 may be expressed at low levels outside olfactory and reproductive tissues

  • Solution: Use signal amplification techniques such as tyramide signal amplification for immunohistochemistry or highly sensitive detection methods for Western blot

• Post-translational modifications:

  • GPCRs like OR4C13 undergo various post-translational modifications that can affect antibody binding

  • Solution: Use antibodies targeting unmodified regions or multiple antibodies targeting different epitopes

• Membrane protein extraction:

  • As a 7-transmembrane protein, OR4C13 can be difficult to extract and maintain in its native conformation

  • Solution: Use specialized detergent-based extraction methods optimized for membrane proteins

• Functional characterization:

  • Determining the ligands and functional roles of OR4C13 outside the olfactory system is challenging

  • Solution: Consider heterologous expression systems coupled with calcium imaging or other functional assays to identify potential ligands and signaling pathways

How can I design experiments to investigate OR4C13 function in non-olfactory tissues?

To investigate OR4C13 function in non-olfactory tissues such as reproductive or neurological tissues, consider the following experimental approaches:

• Expression manipulation studies:

  • Knockdown: Use OR4C13 shRNA lentiviral particles (e.g., sc-96386-V) to reduce expression

  • Overexpression: Create expression constructs for OR4C13 and transfect into relevant cell types

  • Measure phenotypic changes (e.g., sperm motility, neuronal activity)

• Localization and interaction studies:

  • Co-immunoprecipitation to identify protein interaction partners

  • Proximity ligation assays to confirm protein-protein interactions in situ

  • Co-localization with known signaling components using dual immunofluorescence

• Functional assays:

  • For reproductive studies: Assess sperm parameters (motility, chemotaxis, acrosome reaction) after OR4C13 manipulation

  • For neurological studies: Measure calcium signaling or other second messengers in neuronal cultures with manipulated OR4C13 expression

• Comparative expression analysis:

  • Compare OR4C13 expression between normal and pathological conditions using antibody-based techniques

  • Example: The differential expression observed between normal testicular tissue and tissue from patients with spermatocyte maturation arrest

• Animal models:

  • Generate or utilize OR4C13 knockout models to assess physiological roles in vivo

  • Evaluate reproductive parameters or neurological function in these models

What controls should be included when using OR4C13 antibodies for research?

When designing experiments with OR4C13 antibodies, include these essential controls:

• Positive tissue controls:

  • Testicular tissue (especially spermatocytes and spermatids)

  • Epididymal tissue

  • Olfactory epithelium

• Negative controls:

  • Primary antibody omission

  • Isotype control antibody

  • Tissues known not to express OR4C13

  • OR4C13 knockdown samples (using shRNA)

• Peptide blocking controls:

  • Pre-incubate antibody with immunizing peptide

  • Should abolish specific staining

• Multiple antibody validation:

  • Use antibodies targeting different epitopes of OR4C13

  • Consistent staining patterns increase confidence in specificity

• Loading controls for Western blots:

  • Include housekeeping proteins (e.g., actin)

  • Ensure equal loading across samples

• Technical controls:

  • Include both male and female samples when studying sex-specific tissues

  • Age-matched controls when studying developmental or age-related changes

  • Parallel processing of experimental and control samples

These controls help ensure the reliability and interpretability of results when using OR4C13 antibodies in research.

Why might I see inconsistent OR4C13 staining patterns in my experiments?

Several factors can contribute to inconsistent OR4C13 staining patterns:

• Fixation effects:

  • Overfixation can mask epitopes

  • Published protocols used 2% paraformaldehyde for 20 minutes at room temperature for testicular tissue

  • Different fixatives may be optimal for different tissues

• Antibody specificity issues:

  • Cross-reactivity with other olfactory receptors

  • Batch-to-batch variations in polyclonal antibodies

  • Solution: Validate each antibody lot using positive and negative controls

• Antigen retrieval effectiveness:

  • Inadequate antigen retrieval can result in weak or absent staining

  • Optimize antigen retrieval methods for your specific tissue

• Variable expression levels:

  • OR4C13 expression may vary with physiological state

  • In testicular tissue, expression differs between cell types (spermatogonia, spermatocytes, spermatids)

  • Hormonal influences may affect expression levels

• Technical factors:

  • Antibody concentration: Titrate to optimize signal-to-noise ratio

  • Incubation conditions: Temperature and duration affect staining intensity

  • Detection system sensitivity: Consider signal amplification for low-expressing tissues

How can I optimize Western blot protocols for OR4C13 detection?

Based on published research, these optimization steps may improve OR4C13 detection by Western blot:

• Sample preparation:

  • For seminal plasma: Use Reducing Laemmli buffer with 2-mercaptoethanol

  • For tissues: Consider specialized extraction buffers for membrane proteins

  • Heat samples at 95°C for 5 minutes

• Gel conditions:

  • OR4C13 has a predicted molecular weight of ~34 kDa

  • Use 10-12% acrylamide gels for optimal resolution in this range

• Transfer conditions:

  • Transfer to PVDF membrane rather than nitrocellulose

  • Consider semi-dry transfer for more efficient transfer of membrane proteins

• Blocking optimization:

  • Test different blocking agents (BSA vs. milk) to reduce background

  • Optimize blocking time and temperature

• Antibody conditions:

  • Dilution range: 1:500-1:1000 for most anti-OR4C13 antibodies

  • Incubate overnight at 4°C to improve specific binding

  • Include 0.1% Tween-20 in antibody diluent to reduce non-specific binding

• Detection system:

  • Enhanced chemiluminescence (ECL) has been successfully used

  • Consider more sensitive detection for low abundance samples

• Controls:

  • Include positive control (e.g., testicular tissue lysate)

  • Use actin as loading control

What are the latest research findings about OR4C13 beyond the olfactory system?

Recent studies have expanded our understanding of OR4C13's roles beyond olfaction:

• Reproductive biology:

  • OR4C13 has been detected in seminal plasma through high-resolution mass spectrometry approaches

  • Immunolocalization studies showed expression in sperm cells (acrosome, midpiece, flagellum), testicular tissue (spermatogonia, spermatocytes, spermatids), and epididymis

  • Differential expression patterns observed between normal fertile individuals and those with spermatocyte maturation arrest

• Neurology and traumatic brain injury:

  • Expression analysis of neuronally derived extracellular vesicles showed significant differences in OR4C13 levels between traumatic brain injury patients and controls

  • Specifically, differences were observed in both severe TBI (p = 0.0053) and mild TBI (p < 0.001)

• Chronic cough research:

  • Genomic studies of chronic cough identified OR4C13 as one of the novel genes involved in neurological processes associated with cough

  • This finding suggests olfactory receptors may play roles in cough hypersensitivity and neuronal dysfunction

• Potential moonlighting functions:

  • The presence of OR4C13 in diverse tissues suggests it may have multiple functions depending on cellular context

  • Similar to other olfactory receptors that have been shown to function in chemotaxis, these non-canonical roles are an emerging area of research

What approaches might advance our understanding of OR4C13 function?

Several innovative approaches could further elucidate OR4C13 function:

• Single-cell transcriptomics:

  • Characterize cell type-specific expression patterns of OR4C13 in reproductive and neurological tissues

  • Identify co-expressed genes that might participate in the same signaling pathways

• CRISPR/Cas9 genome editing:

  • Generate OR4C13 knockout models to study physiological roles

  • Create reporter systems by tagging endogenous OR4C13 to study localization and trafficking

• Ligand identification:

  • Utilize high-throughput screening approaches to identify potential ligands for OR4C13 outside the olfactory system

  • Investigate whether the same or different ligands activate OR4C13 in different tissue contexts

• Structural biology approaches:

  • Determine the 3D structure of OR4C13 to understand ligand binding and activation mechanisms

  • Use this information to develop specific agonists or antagonists for functional studies

• Multi-omics integration:

  • Combine proteomics, transcriptomics, and metabolomics data to understand OR4C13 in broader signaling networks

  • This might reveal unexpected connections to disease pathways