ENT1 is a 50 kDa transmembrane protein belonging to the solute carrier family 29. It facilitates bidirectional transport of nucleosides like adenosine, essential for cellular processes such as DNA synthesis and signaling . ENT1 antibodies recognize specific epitopes, enabling detection in diverse biological samples.
Key features of ENT1 protein:
| Property | Detail |
|---|---|
| Gene Symbol | ENT1/SLC29A1 |
| UniProt ID | Q99808 |
| Calculated Molecular Weight | 50 kDa |
| Observed Molecular Weight | 70 kDa (post-translational modification) |
The ENT1 antibody (e.g., Proteintech 29862-1-AP) is widely used in biomedical research for:
Western Blot (WB): Detects ENT1 in HCT 116 and HeLa cell lines, mouse heart/kidney/liver tissues, and rat liver .
Immunohistochemistry (IHC): Identifies ENT1 in human colon cancer and lymphoma tissues .
Immunofluorescence (IF) and ELISA: Validated in peer-reviewed studies .
Recommended dilutions:
| Application | Dilution Range |
|---|---|
| Western Blot | 1:500–1:2000 |
| IHC | 1:50–1:500 |
ENT1 antibodies undergo rigorous validation to ensure specificity:
Immunogen: Fusion protein Ag32003, designed to minimize cross-reactivity .
Species Reactivity: Confirmed in human, mouse, and rat samples .
Epitope Validation: Techniques include knockout (KO) cell line comparisons and antigen-retrieval optimization (e.g., TE buffer pH 9.0 for IHC) .
Critical validation steps from NeuroMab :
Parallel screening via ELISA and transfected cell assays.
Functional testing in target tissues (e.g., brain samples for neurological studies).
Open-access protocols and reproducibility checks.
Cancer Biology: ENT1 is overexpressed in certain cancers, correlating with chemotherapeutic nucleoside analog uptake (e.g., gemcitabine in pancreatic cancer) .
Neurological Studies: ENT1 regulates adenosine levels in the brain, impacting sleep-wake cycles and neuroprotection .
| Study Focus | Model System | Major Finding | Source |
|---|---|---|---|
| Nucleoside Transport | HCT 116 cells | ENT1 mediates adenosine uptake | |
| Drug Resistance | Mouse liver tissue | ENT1 downregulation linked to gemcitabine resistance |
Drawing from general antibody classification principles, ENTR1 antibodies can be categorized into three main types: polyclonal, monoclonal, and recombinant. Each type offers distinct advantages in research applications. Polyclonal antibodies recognize multiple epitopes on the ENTR1 protein, providing strong signal amplification but potentially lower specificity. Monoclonal antibodies bind to a single epitope, offering high specificity but potentially more limited detection capabilities. Recombinant antibodies, produced through in vitro methods, generally demonstrate superior performance characteristics compared to traditional monoclonal or polyclonal antibodies . For optimal experimental design, researchers should consider selecting recombinant ENTR1 antibodies when available, as studies have demonstrated that recombinant antibodies generally outperform monoclonal or polyclonal antibodies in terms of specificity and reproducibility .
Proper validation of ENTR1 antibodies requires a comprehensive approach using knockout cell lines as negative controls. Following standardized characterization methodologies, researchers should validate ENTR1 antibodies for each specific application (Western blot, immunoprecipitation, immunofluorescence) separately . The validation process should include:
Specificity testing using ENTR1 knockout cell lines
Sensitivity assessment across a range of ENTR1 expression levels
Reproducibility testing across multiple experimental conditions
Cross-reactivity evaluation against similar proteins
Research indicates that more than 50% of commercially available antibodies fail in one or more applications, highlighting the critical importance of thorough validation . A successful validation approach would include parental cell lines expressing sufficient levels of ENTR1 protein alongside knockout controls, with detection thresholds appropriate for antibodies with binding affinities in the 1-50 nM range .
When designing experiments to study ENTR1 expression in cancer tissues, implement a multi-modal approach that combines complementary techniques:
Immunohistochemistry (IHC): For tissue localization and expression level assessment
Use validated ENTR1-specific antibodies
Include appropriate positive and negative controls
Employ standardized scoring systems (e.g., H-score, Allred score)
Compare MAC tissues with adjacent normal tissues
RNA sequencing: For gene expression profiling
Functional validation:
This approach allows for comprehensive characterization of ENTR1's role in cancer progression and its potential as a prognostic biomarker. The experimental design should incorporate appropriate statistical analyses, including Wilcoxon and Kruskal-Wallis tests to analyze associations between ENTR1 expression and clinical characteristics .
For optimal immunoprecipitation (IP) of ENTR1, consider the following methodological approach:
Antibody selection:
Lysis buffer optimization:
Use buffers containing 1% NP-40 or Triton X-100 for initial extraction
Include protease inhibitors to prevent protein degradation
Adjust salt concentration (150-300 mM NaCl) based on ENTR1's interaction strength with binding partners
Protocol parameters:
Pre-clear lysates with protein A/G beads to reduce non-specific binding
Incubate antibodies with lysates at 4°C overnight with gentle rotation
Perform stringent washing steps (at least 4-5 washes) to reduce background
Elute under denaturing conditions for direct analysis or native conditions for functional studies
Controls:
The success of ENTR1 immunoprecipitation should be verified through Western blotting using a separate validated anti-ENTR1 antibody that recognizes a different epitope to confirm specificity of the pulled-down protein.
For quantitative assessment of ENTR1 protein levels using Western blotting, follow these methodological guidelines:
Sample preparation:
Use standardized protein extraction protocols with phosphatase and protease inhibitors
Determine protein concentration using BCA or Bradford assays
Load equal amounts of protein (20-50 μg) per lane
Antibody selection and optimization:
Use antibodies specifically validated for Western blot applications
Determine optimal antibody dilution through titration experiments
Select secondary antibodies with minimal cross-reactivity
Quantification methodology:
Use housekeeping proteins (β-actin, GAPDH) or total protein stains as loading controls
Employ digital image analysis software for densitometry
Calculate relative expression as ratio of ENTR1 signal to loading control
Create standard curves using recombinant ENTR1 protein for absolute quantification
Quality control measures:
For comparing ENTR1 expression between different samples (e.g., tumor vs. normal tissue), include both sample types on the same blot to minimize technical variation, and normalize to appropriate loading controls to account for differences in total protein content.
To investigate the relationship between ENTR1 expression and immune cell infiltration, implement this comprehensive approach:
Computational analysis of RNA-seq data:
Utilize algorithms like CIBERSORT to quantify 22 distinct immune cell populations
Apply ESTIMATE method to calculate immune, stromal, and ESTIMATE scores
Perform correlation analysis using Pearson's correlation coefficient between ENTR1 expression and immune parameters
Stratify samples into high and low ENTR1 expression groups based on median expression
Multiplex immunofluorescence:
Use validated antibodies against ENTR1 and immune cell markers (CD8, CD4, etc.)
Employ spectral unmixing to distinguish multiple fluorophores
Quantify co-localization patterns using digital image analysis
Flow cytometry of disaggregated tumor samples:
Create single-cell suspensions from fresh tumor samples
Stain for ENTR1 and immune cell markers
Analyze correlations between ENTR1 expression and immune cell percentages
Validation experiments:
Use in vitro co-culture systems to assess direct effects of ENTR1 expression on immune cell function
Perform knockdown/overexpression studies to establish causality
Research has demonstrated that ENTR1 expression positively correlates with CD8+ T cell infiltration (p = 0.01) while showing negative correlation with stromal scores (correlation coefficient = -0.24, p = 0.03) . These findings suggest a potential role for ENTR1 in modulating the tumor immune microenvironment, particularly in relation to cytotoxic T cell recruitment.
To investigate the association between ENTR1 and cancer cell stemness, employ these methodological approaches:
Bioinformatic analysis:
Calculate RNA-based stemness scores (RNAss) using established algorithms
Perform correlation analysis between ENTR1 expression and stemness scores
Conduct Gene Set Enrichment Analysis (GSEA) to identify stemness-related pathways
Compare ENTR1 expression with known stemness markers (NANOG, OCT4, SOX2)
Functional stemness assays:
Sphere formation assays with ENTR1 knockdown/overexpression cells
Serial dilution xenograft experiments to assess tumor-initiating capacity
Side population analysis to identify cells with stem-like properties
Limiting dilution assays to quantify stem cell frequency
Molecular analysis:
ChIP-seq to identify ENTR1-associated regulatory elements in stemness genes
RNA-seq to profile transcriptional changes following ENTR1 modulation
Single-cell RNA-seq to identify ENTR1-high subpopulations with stemness properties
Current research has established a significant positive correlation between ENTR1 expression and cell stemness in mucinous adenocarcinoma (correlation coefficient = 0.44, p < 0.0001) . This suggests that ENTR1 may play a role in maintaining or promoting cancer stem cell properties, potentially contributing to tumor progression and therapeutic resistance.
Developing antibodies with custom specificity profiles for ENTR1 epitopes requires a systematic approach combining experimental selection and computational modeling:
Phage display selection strategy:
Computational modeling and optimization:
Build energy-based models to predict binding specificities
Identify binding modes associated with each epitope
Optimize antibody sequences by minimizing energy functions for desired epitopes while maximizing them for undesired epitopes
Use the model to design novel sequences with predefined binding profiles
Experimental validation:
Synthesize and express designed antibody sequences
Test binding specificity against multiple ENTR1 epitopes
Validate performance in relevant applications (WB, IP, IF)
This approach allows for the development of highly specific antibodies that can discriminate between closely related epitopes, which is particularly valuable for studying specific domains or post-translational modifications of ENTR1. Research has demonstrated that such computational approaches can successfully disentangle different binding modes even when they are associated with chemically very similar ligands .
When encountering non-specific binding with ENTR1 antibodies, implement this systematic troubleshooting approach:
Antibody validation assessment:
Protocol optimization:
Increase blocking stringency (5% BSA or 5% milk in TBS-T)
Optimize antibody concentration through titration experiments
Increase washing duration and number of wash steps
Include competing peptides to block non-specific interactions
Sample preparation improvements:
Pre-clear lysates with protein A/G beads before immunoprecipitation
Use freshly prepared samples to minimize protein degradation
Optimize protein extraction conditions for ENTR1 detection
Application-specific adjustments:
| Application | Troubleshooting Approach |
|---|---|
| Western blot | Use gradient gels to better resolve ENTR1; optimize transfer conditions |
| Immunofluorescence | Implement antigen retrieval; use detergents to improve penetration |
| Flow cytometry | Optimize fixation/permeabilization; include viability dye to exclude dead cells |
| Immunoprecipitation | Pre-clear lysates extensively; use more stringent wash buffers |
Research indicates that more than 50% of commercial antibodies fail in one or more applications , emphasizing the importance of thorough validation and optimization for each specific application.
To comprehensively evaluate ENTR1 antibody quality, assess these key metrics:
Specificity parameters:
Signal-to-noise ratio in Western blots comparing wild-type to ENTR1 knockout cells
Cross-reactivity profile against closely related proteins
Background levels in immunofluorescence using knockout controls
Off-target binding in immunoprecipitation-mass spectrometry experiments
Sensitivity metrics:
Limit of detection (LOD) using recombinant ENTR1 protein dilution series
Dynamic range of quantification
Ability to detect endogenous ENTR1 in different cell types with varying expression levels
Reproducibility assessment:
Intra-assay coefficient of variation (CV) across technical replicates
Inter-assay CV across independent experiments
Lot-to-lot consistency for the same antibody catalog number
Application-specific performance:
| Application | Quality Metrics |
|---|---|
| Western blot | Band specificity; linearity of signal; consistency of molecular weight |
| Immunofluorescence | Signal localization; background levels; staining pattern consistency |
| Immunohistochemistry | Staining intensity; background; correlation with RNA expression |
| Flow cytometry | Population separation; staining index; correlation with other methods |
Research suggests that recombinant antibodies generally demonstrate superior performance compared to monoclonal or polyclonal antibodies , making them the preferred choice for detecting ENTR1 in critical research applications.
When faced with contradictory results from different ENTR1 antibodies, follow this methodological framework for resolution:
Systematic antibody validation:
Test all antibodies against ENTR1 knockout controls
Compare antibody performance across multiple applications
Verify epitope locations and potential overlap between antibodies
Assess if antibodies recognize different ENTR1 isoforms or post-translational modifications
Orthogonal method validation:
Confirm ENTR1 expression using RNA-based methods (qPCR, RNA-seq)
Use genetic approaches (siRNA, CRISPR) to manipulate ENTR1 levels
Apply mass spectrometry to definitively identify ENTR1 protein
Correlate findings with functional assays related to ENTR1 activity
Technical consideration analysis:
Evaluate whether discrepancies are application-specific
Assess if sample preparation methods affect epitope accessibility
Consider fixation and antigen retrieval effects on epitope detection
Examine buffer conditions that might affect antibody performance
Research literature assessment:
Review publications that have used the same antibodies
Contact manufacturers for additional validation data
Consider consulting public antibody validation repositories
Developing prognostic assays using ENTR1 antibodies requires a systematic approach:
Standardized immunohistochemistry protocol:
Select highly validated ENTR1 antibodies with proven specificity
Establish standardized staining protocols and scoring systems
Develop automated image analysis algorithms for quantification
Validate on tissue microarrays with known clinical outcomes
Prognostic model development:
Determine optimal cutoff values for ENTR1 expression
Integrate ENTR1 with other prognostic markers
Perform multivariate analysis adjusting for clinicopathological variables
Validate in independent patient cohorts
Clinical implementation considerations:
Develop standard operating procedures for clinical laboratories
Establish quality control measures for reproducibility
Create reference standards for inter-laboratory comparisons
Design reporting formats with clear clinical interpretation guidelines
To investigate ENTR1's functional mechanisms in cancer progression, implement these methodological approaches:
Genetic manipulation strategies:
CRISPR/Cas9 knockout of ENTR1 in cancer cell lines
Inducible shRNA systems for temporal control of ENTR1 knockdown
Overexpression of wild-type and mutant ENTR1 variants
Domain-specific mutations to identify functional regions
Molecular interaction studies:
Co-immunoprecipitation with validated ENTR1 antibodies
Proximity labeling (BioID, APEX) to identify ENTR1 interaction partners
Yeast two-hybrid or mammalian two-hybrid screening
Pull-down assays with recombinant ENTR1 protein domains
Functional assays:
Cell proliferation, migration, and invasion assays
3D organoid culture systems
In vivo xenograft models with ENTR1-modified cells
Pathway activity assessment using reporter assays
Mechanistic investigations:
Transcriptome analysis following ENTR1 modulation
ChIP-seq to identify ENTR1-associated genomic regions
Protein localization studies using fractionation and imaging
Phospho-proteomic analysis to identify signaling pathways
GSEA analysis has revealed that ENTR1 expression is associated with pyrimidine metabolism (FDR = 0.026) , providing initial insights into potential molecular mechanisms. Additionally, the significant correlation between ENTR1 expression and cancer cell stemness suggests involvement in maintaining stem-like properties in cancer cells , which could be further investigated using the methodologies outlined above.
Developing ENTR1-targeting therapeutic antibodies requires combining antibody engineering principles with thorough understanding of ENTR1 biology:
Target epitope identification:
Identify accessible epitopes on ENTR1 in disease states
Map functional domains critical for ENTR1's pathological role
Assess epitope conservation across species for preclinical testing
Evaluate potential cross-reactivity with related proteins
Antibody format optimization:
Compare conventional IgG formats with alternative scaffolds
Evaluate fragment formats (Fab, scFv) for improved tissue penetration
Consider bispecific formats to engage immune effector cells
Assess antibody-drug conjugate potential if ENTR1 is internalized
Affinity maturation and specificity engineering:
Functional screening:
The computational approach described in the research literature enables the design of antibodies with customized specificity profiles, either with specific high affinity for particular target epitopes or with cross-specificity for multiple targets . This methodology could be applied to develop ENTR1 antibodies with precisely engineered binding properties for therapeutic applications.
To effectively investigate ENTR1 expression in patient-derived xenograft (PDX) models, implement these methodological approaches:
Species-specific antibody selection:
Multi-modal analysis:
Combine immunohistochemistry with RNA-seq for comprehensive profiling
Use RNAscope for in situ visualization of ENTR1 mRNA
Implement laser capture microdissection to separate tumor from stromal components
Apply single-cell analysis techniques to assess heterogeneity
Longitudinal monitoring:
Establish sampling protocols at different stages of PDX establishment
Compare ENTR1 expression between primary tumor and derived PDX models
Track expression changes across PDX passages
Correlate with treatment responses and tumor evolution
Analytical framework:
Develop quantitative scoring systems for ENTR1 protein expression
Implement image analysis algorithms for automated quantification
Apply statistical methods to assess correlations with clinical parameters
Integrate with broader multi-omics datasets from the same models
This approach allows for comprehensive characterization of ENTR1 expression patterns in PDX models, providing insights into its role in tumor maintenance, progression, and response to therapies. Given ENTR1's established association with cell stemness and immune infiltration , PDX models offer valuable opportunities to investigate these relationships in a more physiologically relevant context than conventional cell line models.