Mechanism: The EMC, including COX4NB, enables insertion of tail-anchored and multi-pass transmembrane proteins via a conserved hydrophilic funnel in the ER membrane .
Substrates: Targets include proteins with stop-transfer membrane-anchor sequences .
Energy Metabolism: Highly expressed in heart and skeletal muscle, suggesting roles in mitochondrial function .
Protein Quality Control: Interacts with chaperones like NUTF2 and modulates spliceosome-related pathways .
COX4NB is overexpressed in multiple cancers and correlates with poor survival outcomes:
Immune Evasion: COX4NB upregulation associates with immunosuppressive cell infiltration (e.g., Tregs, monocytes) in renal cell carcinoma .
Oncogenic Pathways: Co-expressed with cell cycle regulators (E2F4, ORC6L) and spliceosome components .
| Application | Catalog # | Host | Reactivity | Source | 
|---|---|---|---|---|
| WB/IHC | bs-8310R | Rabbit | Human, Mouse, Rat | Bioss | 
| IF/ELISA | SAB4301145 | Rabbit | Human | Sigma-Aldrich | 
COX4NB’s involvement in membrane protein biogenesis and cancer pathways positions it as a potential biomarker or therapeutic target. Its interaction with immune infiltrates in tumors highlights dual roles in protein homeostasis and tumor microenvironment remodeling .
COX4 neighbor, COX4AL, Protein FAM158B, NOC4, C16orf2, chromosome 16 open reading frame 2, C16orf4, chromosome 16 open reading frame 4, family with sequence similarity 
158-member B.
COX4NB (cytochrome oxidase subunit IV gene neighbor) is a protein-coding gene located adjacent to the COX4I1 gene, which encodes the cytochrome c oxidase subunit IV. COX4NB is not a component of the cytochrome oxidase complex itself but is named for its genomic proximity to COX4I1. Recent studies have investigated potential functional relationships between COX4NB and mitochondrial energy metabolism due to this genetic proximity . The protein has been identified as participating in various cellular processes, including protein binding interactions with other human proteins such as TTC35, which may suggest roles in protein complex formation and stability.
Methodologically, to elucidate the function of COX4NB, researchers typically employ gene knockout/knockdown experiments, co-immunoprecipitation assays to validate protein interactions, and subcellular localization studies using fluorescent tags or immunocytochemistry.
COX4NB shows differential expression across human tissues, with notable expression patterns in tissues with high metabolic demands. Expression profiling studies using both microarray and RNA-seq approaches have demonstrated tissue-specific regulation mechanisms.
Methodologically, researchers investigating COX4NB expression should consider:
Using qRT-PCR with tissue-specific panels
Analyzing publicly available gene expression databases (GTEx, Human Protein Atlas)
Employing chromatin immunoprecipitation (ChIP) to identify transcription factors regulating COX4NB
Conducting promoter analysis to identify regulatory elements
The regulation of COX4NB appears to involve both tissue-specific transcription factors and epigenetic mechanisms that warrant further investigation in experimental models.
When investigating COX4NB protein interactions, researchers should consider multiple complementary approaches:
| Technique | Application | Advantages | Limitations | 
|---|---|---|---|
| Yeast Two-Hybrid | Initial screening | High-throughput capability | Prone to false positives | 
| Co-immunoprecipitation | Validation | Detects endogenous interactions | Requires quality antibodies | 
| Proximity Ligation Assay | In situ detection | Visualizes interactions in native context | Technical complexity | 
| BioID/APEX | Proximity labeling | Identifies weak/transient interactions | Potential off-target labeling | 
| Protein Microarrays | Broad screening | Systematic approach | High cost, limited coverage | 
The choice of experimental approach depends on research questions and available resources. For studying TTC35 binding to COX4NB, a combination of co-immunoprecipitation followed by mass spectrometry has proven effective in identifying interaction partners . When designing these experiments, consider:
Both N- and C-terminal tags to minimize interference with protein binding domains
Multiple cell types to account for tissue-specific interaction partners
Different cellular conditions (stress, differentiation) to capture context-dependent interactions
Appropriate controls for antibody specificity and binding
When manipulating COX4NB expression in human cell models, several approaches have proven effective:
| Method | Application | Efficiency | Considerations | 
|---|---|---|---|
| CRISPR-Cas9 | Complete knockout | High (>90% with optimization) | Potential off-target effects | 
| siRNA/shRNA | Transient knockdown | Variable (60-90%) | Incomplete silencing | 
| Overexpression vectors | Gain-of-function | Cell type dependent | Non-physiological expression levels | 
| Inducible systems | Temporal control | Moderate to high | System leakiness | 
| Base editing | Point mutations | Moderate | Limited to certain mutation types | 
For studying COX4NB function in relation to its binding partners like TTC35 or CGI-112, CRISPR-Cas9 has emerged as the preferred method due to its precision and efficiency . When designing gene manipulation experiments:
Validate knockdown/knockout efficiency using both RNA and protein detection methods
Include appropriate controls for off-target effects
Consider rescue experiments to confirm specificity of observed phenotypes
Select cell lines that express COX4NB at detectable levels
Investigating COX4NB's role in disease models requires careful consideration of molecular phenotypes as intermediate outcomes. Effective assessment strategies include:
Integrating genotype-phenotype correlations across multiple experimental platforms
Examining potential intermediate molecular phenotypes that might be modulated by genetic variants
Assessing COX4NB expression in relevant cellular contexts under disease-mimicking conditions
Utilizing patient-derived samples when possible to validate findings from model systems
Molecular phenotyping approaches that have proven valuable include:
RNA-seq for transcriptome-wide effects of COX4NB manipulation
Proteomics to identify altered protein networks
Metabolomics to detect changes in cellular metabolism
Chromatin state analysis to assess epigenetic alterations
When investigating a protein like COX4NB that may influence multiple pathways, researchers should employ a systems biology approach that integrates data across these molecular phenotyping platforms . This can reveal unexpected connections between COX4NB and cellular processes that might not be apparent from targeted analyses.
When analyzing COX4NB genetic variations in large genomic datasets, several bioinformatic approaches have proven valuable:
| Approach | Application | Strengths | Considerations | 
|---|---|---|---|
| eQTL analysis | Expression correlation | Links variants to expression | Requires matched genotype/expression data | 
| Pathway enrichment | Functional context | Provides biological meaning | Dependent on pathway database quality | 
| Network analysis | Interaction mapping | Reveals functional clusters | Complex interpretation | 
| Machine learning | Pattern recognition | Can identify subtle signals | Requires large training datasets | 
| Cross-phenotype analysis | Pleiotropic effects | Identifies multi-trait associations | Statistical complexity | 
For analyzing COX4NB variants, researchers should:
Consider tissue-specific eQTL analyses as genetic effects may be context-dependent
Employ both cis and trans eQTL analysis to identify regulatory relationships
Use conditional analysis to distinguish independent signals within the locus
Account for population structure in genetic association studies
Validate bioinformatic predictions with experimental approaches
When conducting these analyses, researchers should be aware that non-coding variants near COX4NB may influence gene regulation through chromatin modifications, as suggested by studies of H3K4me3 marks in T cells . This highlights the importance of integrating epigenomic data with genetic variation analysis.
Contradictory findings about COX4NB function across different experimental systems are not uncommon and require systematic approaches to resolve:
Perform rigorous cross-platform validation using multiple cell types and experimental conditions
Standardize experimental protocols to minimize technical variability
Consider context-dependent effects based on cell type, developmental stage, or environmental conditions
Directly compare contradictory models side-by-side in the same laboratory
Conduct meta-analysis of published data to identify patterns in results
When encountering contradictions in COX4NB research:
Examine differences in experimental conditions that might explain divergent results
Consider cell-specific factors that might influence COX4NB function
Evaluate antibody specificity and validation in protein detection experiments
Assess whether genetic background effects might contribute to observed differences
Determine if post-translational modifications affect protein function in different contexts
Researchers should systematically document and report variables that might influence experimental outcomes when studying COX4NB, facilitating more reliable cross-study comparisons.
Current technical limitations in studying COX4NB protein structure include:
| Limitation | Challenge | Potential Solutions | 
|---|---|---|
| Protein solubility | Difficulty in purification | Optimized buffer conditions; fusion tags | 
| Crystallization | Challenging for dynamic proteins | Cryo-EM; NMR for domains | 
| Conformational heterogeneity | Multiple structural states | Single-particle analysis; computational modeling | 
| Post-translational modifications | Structural variability | Site-specific incorporation of modified residues | 
| Interaction-dependent conformations | Structure changes upon binding | Cross-linking MS; hydrogen-deuterium exchange | 
To overcome these limitations, researchers should consider:
Employing integrative structural biology approaches that combine multiple techniques
Using AlphaFold2 or similar AI-based prediction tools to generate initial structural models
Focusing on functional domains rather than whole protein when purification is challenging
Developing nanobodies or other stabilizing agents to capture specific conformational states
Applying in-cell structural techniques to observe the protein in its native environment
When studying COX4NB interactions with binding partners like TTC35, researchers should consider how these interactions might induce conformational changes that affect function or stability .
Single-cell technologies offer powerful approaches to understand COX4NB function in heterogeneous populations:
Single-cell RNA-seq can reveal cell type-specific expression patterns and regulatory relationships
Single-cell proteomics can detect variation in COX4NB protein levels and modification states
Single-cell ATAC-seq can identify cell type-specific regulatory elements controlling COX4NB expression
Spatial transcriptomics can map COX4NB expression in tissue microenvironments
Cell lineage tracing can determine how COX4NB expression changes during differentiation
These approaches are particularly valuable when:
Studying tissues with multiple cell types
Investigating rare cell populations with unique COX4NB expression patterns
Examining COX4NB regulation during development or disease progression
Assessing cell-to-cell variability in response to perturbations
When designing single-cell experiments involving COX4NB, researchers should:
Include appropriate cell type identification markers
Consider temporal dynamics of expression
Account for technical variability in single-cell measurements
Validate findings using orthogonal approaches like immunofluorescence
Employ computational methods specifically designed for single-cell data analysis
The implications of COX4NB genetic variations for personalized medicine are an emerging area of research:
Genetic variants affecting COX4NB expression or function may influence disease susceptibility or progression
Pharmacogenomic studies suggest COX4NB variations could affect response to certain therapeutic agents
Integration of genotype data with molecular phenotypes can help stratify patients for targeted interventions
Tissue-specific eQTL effects may necessitate context-specific therapeutic approaches
When investigating COX4NB variations in clinical contexts, researchers should:
Conduct well-powered genetic association studies with adequate representation of diverse populations
Consider gene-environment interactions that may modify genetic effects
Validate functional consequences of variants using cellular and animal models
Develop biomarkers for monitoring COX4NB-related pathways in patients
Explore potential for targeting COX4NB or its interaction partners therapeutically
As with other potential biomarkers, the clinical utility of COX4NB variations should be rigorously tested through prospective studies before implementation in personalized medicine applications.
Investigating COX4NB involvement in protein complexes requires specialized approaches:
| Method | Application | Advantages | Considerations | 
|---|---|---|---|
| Blue Native PAGE | Native complex separation | Preserves complex integrity | Limited resolution for large complexes | 
| Size Exclusion Chromatography | Complex purification | Quantitative sizing | Requires substantial starting material | 
| Sucrose Gradient Ultracentrifugation | Complex separation | High resolution | Labor intensive | 
| Cross-linking Mass Spectrometry | Interface mapping | Identifies interaction sites | Complex data analysis | 
| Cryo-electron Microscopy | Structure determination | Near-atomic resolution | Technical expertise required | 
When studying COX4NB-containing complexes:
Consider stabilization methods to preserve transient interactions
Use both detergent-based and detergent-free extraction methods to compare results
Employ tagged versions of COX4NB for affinity purification, with controls for tag interference
Validate complex components through reciprocal pulldowns
Assess stoichiometry of complex components using quantitative proteomics
These approaches have been particularly valuable for investigating potential interactions between COX4NB and proteins like TTC35 and CGI-112 , helping to elucidate functional relationships that may have implications for cellular physiology and disease mechanisms.
Integrating multi-omics data for COX4NB research requires systematic approaches:
Coordinate sample collection across platforms to minimize technical and biological variability
Implement rigorous quality control procedures specific to each data type
Apply appropriate normalization methods for cross-platform integration
Utilize computational frameworks specifically designed for multi-omics analysis
Validate key findings using targeted experimental approaches
Effective integration strategies include:
Building regulatory networks that incorporate transcriptomic, proteomic, and epigenomic data
Applying Bayesian integration methods to identify causal relationships
Using dimension reduction techniques to identify patterns across data types
Developing predictive models that incorporate multiple data types
Employing visualization tools that effectively represent complex multi-dimensional relationships
When studying intermediate molecular phenotypes potentially influenced by COX4NB, a multi-omics approach can reveal mechanisms that would not be apparent from single-platform analyses . This approach is particularly valuable for identifying context-dependent functions and regulatory relationships that may vary across cell types or conditions.
The recombinant human COX4NB protein consists of 225 amino acids and has a predicted molecular mass of 25.6 kDa. When analyzed under reducing conditions using SDS-PAGE, it migrates as an approximately 27 kDa band . The protein is expressed in various tissues, including the liver, pancreas, heart, lung, kidney, brain, skeletal muscle, and placenta. Expression levels are highest in the pancreas and moderate in the heart, skeletal muscle, and placenta .
The recombinant human COX4NB protein is typically produced in E. coli. The protein is expressed with a polyhistidine tag (His-tag) at the N-terminus, which facilitates its purification using conventional chromatography techniques . The purity of the recombinant protein is greater than 95%, as determined by SDS-PAGE .
Recombinant human COX4NB protein is usually provided as a lyophilized powder, which is stable for up to twelve months when stored at -20°C to -80°C under sterile conditions. It is recommended to aliquot the protein to avoid repeated freeze-thaw cycles . For reconstitution, specific buffer information and instructions are provided with the product .