STRN Antibody

What is STRN protein and why is it important in research?

STRN (striatin, calmodulin binding protein) is an 86 kDa protein (calculated molecular weight) that typically appears at 110 kDa in experimental conditions. It is found in all mammalian cells and plays critical roles in vesicular transport, dendrite growth, and cellular signaling pathways. STRN binds Protein phosphatase 2A (PP2A) A and C subunits and calmodulin, modulating PP2A activity. It also interacts with the human homolog of the yeast protein Mob1, implicated in mitotic progression. STRN belongs to a protein family that includes SG2NA and Zinedin . Research interest in STRN has increased due to its involvement in cancer progression and the discovery of STRN-ALK fusion proteins as potential therapeutic targets in multiple cancers .

How do I select the appropriate STRN antibody for my research application?

Selection should be based on multiple factors including:

• Target species reactivity: Available STRN antibodies show reactivity with human, mouse, and rat samples. Confirm cross-reactivity with your experimental model .

• Validated applications: Choose antibodies validated for your specific application:

  Application	Available Antibody Options	Recommended Dilution Range
  Western Blot (WB)	Multiple options including 21624-1-AP	1:2000-1:10000
  Immunohistochemistry (IHC)	21624-1-AP, A15861	1:50-1:500
  Immunofluorescence (IF)/ICC	21624-1-AP	1:10-1:100
  Flow Cytometry (Intra)	21624-1-AP	0.40 μg per 10^6 cells
  Immunoprecipitation (IP)	21624-1-AP	0.5-4.0 μg for 1.0-3.0 mg lysate
  ELISA	21624-1-AP, 85058-2-PBS	Application-dependent

• Antibody format: Consider polyclonal (broader epitope recognition) versus monoclonal/recombinant (higher specificity and reproducibility) based on your research needs .

• Storage buffer compatibility: Some applications may require specific buffer conditions (e.g., 85058-2-PBS in PBS only for conjugation readiness) .

What are the key differences between polyclonal and recombinant monoclonal STRN antibodies?

Polyclonal STRN antibodies (e.g., 21624-1-AP):

• Recognize multiple epitopes on the STRN protein

• Typically show broader reactivity across species (human, mouse, rat)

• Useful when protein conformation might vary across experimental conditions

• May have batch-to-batch variability

• Generally stored in PBS with glycerol and sodium azide

Recombinant monoclonal STRN antibodies (e.g., 85058-2-PBS):

• Target specific epitopes with higher precision

• Produced using recombinant technology for batch-to-batch consistency

• Offer future security of supply and easy scale-up

• Often available in conjugation-ready formats (PBS only, without BSA/azide)

• Ideal for applications requiring matched pairs like multiplex assays

What are the optimal conditions for using STRN antibodies in Western blotting?

For optimal Western blot results with STRN antibodies:

• Sample preparation: STRN has been successfully detected in various cell and tissue lysates including A549 cells, rat/mouse brain tissue, NIH/3T3 cells, HEK-293T cells, HeLa cells, and Jurkat cells .

• Antibody dilution: For polyclonal antibodies like 21624-1-AP, use dilutions between 1:2000-1:10000. Titrate in your specific system for optimal results .

• Expected band size: STRN has a calculated molecular weight of 86 kDa but is typically observed at approximately 110 kDa .

• Controls: Include positive controls from validated cell lines (e.g., HeLa cells) and negative controls through STRN knockdown (e.g., using siRNA as described in publication ).

• Detection system: Standard chemiluminescence systems are compatible with these antibodies.

• Troubleshooting: If non-specific bands appear, further optimize antibody dilution or consider using recombinant monoclonal antibodies for higher specificity.

How do I optimize STRN antibody conditions for immunohistochemistry?

For successful IHC with STRN antibodies:

• Tissue preparation: STRN antibodies have been validated on mouse brain tissue and human liver tissue .

• Antigen retrieval: Use TE buffer pH 9.0 (recommended) or citrate buffer pH 6.0 (alternative) for optimal epitope exposure .

• Antibody dilution: Start with 1:50-1:500 dilution range and optimize for your specific tissue/fixation method .

• Detection: STRN is primarily expressed in the cytoplasm of cells, as documented in HCC studies .

• Controls: Include tissue samples with known STRN expression (e.g., brain tissue) as positive controls.

• Scoring system: For semi-quantitative analysis, consider implementing a staining index (SI) system similar to that used in HCC research .

How can I assess antibody binding strength in STRN-related studies?

When evaluating antibody-antigen interactions in STRN studies:

• Chaotrope-based assays:

  • Disrupt antibody-antigen complexes using thiocyanate (SCN-) or urea

  • Calculate avidity index: (reciprocal titer after chaotrope exposure ÷ reciprocal titer without chaotrope) × 100%

  • Alternatively, use the functional affinity index (FAI) based on EC50 values or Bmax index

• Surface plasmon resonance (SPR):

  • Measures real-time binding kinetics including association and dissociation rates

  • Can determine average off-rate constants for polyclonal antibodies

  • Allows measurement of binding to various STRN epitopes under different conditions

• Titration series:

  • Compare EC50 values across different antibodies or experimental conditions

  • Assess both binding titer and binding strength independently

These methods provide different but complementary information about antibody binding characteristics in polyclonal sera, with kinetic binding assays offering advantages for conformationally complex antigens .

How should I design knockdown experiments to validate STRN antibody specificity?

For proper STRN knockdown validation:

• siRNA design: Target specific STRN sequences as validated in published research. Example target sequences used successfully:

  siRNA Type	Target Sequence	Reference
  STRN siRNA	Refer to Table 2 in the published study

• Transfection protocol: Use Lipofectamine™ 2000 (Invitrogen) for efficient delivery of siRNA .

• Controls: Include negative control (NC) siRNA with non-targeting sequence .

• Validation methods:

  • Western blot: Primary verification method

  • Immunofluorescence assays: Secondary confirmation

• Knockdown efficiency assessment: Multiple siRNAs may show different inhibitory effects; select the most effective one (e.g., siRNA2 demonstrated greatest inhibition in published work) .

• Timeline: Allow 48-72 hours post-transfection before conducting functional assays or antibody validation tests .

What experimental controls are essential when working with STRN antibodies?

Essential controls include:

• Positive tissue/cell controls:

  • Brain tissue (mouse/rat): High endogenous STRN expression

  • HeLa, HEK-293T, and Jurkat cells: Validated positive expression

  • Liver tissue (for IHC applications)

• Negative controls:

  • Primary antibody omission

  • Isotype control (rabbit IgG)

  • STRN-knockdown samples via siRNA

• Cross-reactivity controls:

  • Verify specificity against other striatin family members (e.g., SG2NA, Zinedin)

• Technical controls:

  • Loading controls for Western blot (e.g., β-actin, GAPDH)

  • Tissue processing controls for IHC

  • Secondary antibody-only controls

• Dilution series:

  • Test multiple antibody dilutions to establish optimal signal-to-noise ratio

How can I design experiments to investigate STRN-protein interactions?

To investigate STRN-protein interactions:

• Co-immunoprecipitation (Co-IP):

  • Use 0.5-4.0 μg STRN antibody per 1.0-3.0 mg of total protein lysate

  • Validated in mouse brain tissue for STRN interactions

  • Probe for known interaction partners: PP2A subunits, calmodulin, Mob1

• Proximity ligation assays (PLA):

  • Visualize protein-protein interactions in situ

  • Combine STRN antibody with antibodies against potential interaction partners

  • Requires antibodies from different host species or isotypes

• Pull-down assays:

  • Use recombinant STRN protein as bait

  • Identify novel interaction partners through mass spectrometry

• Functional validation:

  • Assess effects of STRN knockdown on localization/function of interaction partners

  • Use site-directed mutagenesis to identify critical interaction domains

How do I interpret discrepancies between calculated and observed molecular weights for STRN?

STRN has a calculated molecular weight of 86 kDa based on its 780 amino acid sequence, but is consistently observed at approximately 110 kDa in Western blots . This discrepancy can be explained by:

• Post-translational modifications:

  • Phosphorylation sites on STRN may alter mobility

  • Potential glycosylation or other modifications

• Protein structure considerations:

  • Tertiary structure may affect SDS binding and gel migration

  • Charged amino acid composition can influence apparent molecular weight

• Experimental validation:

  • When troubleshooting, compare your observed band with published literature

  • Confirm specificity through siRNA knockdown experiments

  • Consider using multiple antibodies targeting different epitopes

• Fusion protein considerations:

  • Rule out STRN-ALK fusion proteins (which would appear at higher molecular weights) by confirming single band at expected size

  • Note that STRN-ALK fusions have been identified in multiple cancers but require specific detection methods

How do I troubleshoot non-specific binding or high background when using STRN antibodies?

To address non-specific binding issues:

• Western blot troubleshooting:

  • Increase antibody dilution (try 1:5000-1:10000)

  • Optimize blocking conditions (5% non-fat milk or BSA)

  • Increase washing duration and frequency (use 0.1% Tween-20 in TBS/PBS)

  • Reduce exposure time during imaging

  • Consider switching to monoclonal antibodies for higher specificity

• IHC/IF troubleshooting:

  • Optimize antigen retrieval (compare TE buffer pH 9.0 vs. citrate buffer pH 6.0)

  • Titrate antibody concentration (1:50-1:500 range)

  • Include longer blocking steps (10% normal serum from secondary antibody species)

  • Use avidin-biotin blocking for tissues with high endogenous biotin

  • Consider tissue-specific autofluorescence quenching for IF applications

• Flow cytometry troubleshooting:

  • Ensure proper cell permeabilization (STRN is intracellular)

  • Use recommended concentration (0.40 μg per 10^6 cells)

  • Include proper FMO (fluorescence minus one) controls

How should I interpret STRN localization patterns in different cell types?

STRN localization interpretation requires understanding:

• Expected localization pattern:

  • STRN is primarily cytoplasmic in most cell types

  • May show punctate patterns associated with vesicular structures

  • Can interact with membrane-associated protein complexes

• Cell-type specific considerations:

  • Neuronal cells: May show enrichment in dendritic spines

  • Cancer cells: Potential alterations in localization patterns

  • Epithelial cells: Association with cell-cell junctions during EMT

• Co-localization analysis:

  • Consider dual staining with markers for:

    • Cell junctions (E-cadherin)

    • Cytoskeletal elements (vimentin)

    • Signaling complexes (PP2A)

  • Quantify co-localization using appropriate statistical measures

• Functional correlations:

  • Changes in STRN localization during EMT correlate with altered E-cadherin and vimentin expression

  • Cytoplasmic vs. membrane localization may indicate different functional states

How do STRN expression levels correlate with cancer progression and EMT?

Research has established important correlations between STRN and cancer:

• Expression in hepatocellular carcinoma (HCC):

  • STRN is significantly upregulated in HCC tissues compared to adjacent non-tumor tissues

  • Expression correlates positively with lymph node metastasis and TNM stage

  • No significant correlation with patient age, sex, tumor size, histologic grade, cirrhosis, or other clinical parameters

• Functional role in cancer cells:

  • STRN knockdown does not significantly affect cell proliferation or apoptosis

  • STRN positively regulates tumor cell invasion and migration capacities

  • Manipulation of STRN expression leads to morphological changes consistent with EMT modulation

• Molecular mechanisms:

  • STRN knockdown increases E-cadherin expression (epithelial marker)

  • STRN knockdown decreases Vimentin expression (mesenchymal marker)

  • STRN is negatively related to E-cadherin but positively related to Vimentin in HCC tissues

• STRN-ALK fusion relevance:

  • STRN-ALK fusion genes identified as driver mutations in thyroid cancer, NSCLC, colorectal cancer, and renal carcinoma

  • STRN family members (e.g., STRN4) show similar oncogenic potential in various cancers

How can STRN antibodies be used to investigate protein-protein interactions in signaling complexes?

Advanced applications of STRN antibodies in signaling research:

• Striatin-interacting phosphatase and kinase (STRIPAK) complex analysis:

  • Use STRN antibodies to immunoprecipitate entire STRIPAK complex

  • Identify components through mass spectrometry

  • Map interaction domains through deletion mutants

• PP2A activity modulation:

  • Investigate how STRN binding affects PP2A substrate specificity

  • Use STRN antibodies to disrupt specific interactions

  • Compare phosphorylation states of downstream targets

• Calmodulin-dependent signaling:

  • Examine calcium-dependent interaction dynamics

  • Assess competition between calmodulin and other binding partners

  • Use STRN antibodies in calcium-chelating vs. calcium-rich conditions

• Dynamic complex assembly:

  • Employ proximity-based labeling techniques (BioID, APEX) with STRN antibodies

  • Track temporal changes in complex composition during cellular processes

  • Investigate cell cycle-dependent interactions with Mob1

What are the methodological considerations for studying STRN in the context of therapeutic antibody development?

When investigating STRN as a therapeutic target:

• Epitope mapping considerations:

  • Use computational design methods similar to those employed for therapeutic antibodies

  • Consider physics- and AI-based methods for generation and assessment of candidate antibodies

  • Evaluate binding across different domains of STRN protein

• Affinity assessment approaches:

  • Implement surface plasmon resonance (SPR) for kinetic measurements

  • Consider multiple concentration antigen SPR measurements similar to therapeutic antibody evaluation

  • Assess binding strength using chaotrope disruption methods

• Developability assessment:

  • Evaluate aggregation propensity through size-exclusion chromatography

  • Assess thermostability (melting temperature)

  • Consider engineering approaches to improve developability while maintaining binding properties

• Structural validation:

  • Employ structural biology methods (cryo-EM, X-ray crystallography) to validate binding modes

  • Analyze complex formation similar to antibody-antigen complexes in therapeutic contexts

How might emerging antibody technologies enhance STRN research?

Emerging technologies applicable to STRN research:

• Recombinant antibody engineering:

  • Custom epitope targeting for specific STRN domains

  • Development of bispecific antibodies targeting STRN and interaction partners

  • Nanobody development for improved tissue penetration and intracellular delivery

• Machine learning approaches:

  • AI-based antibody design methods similar to those used in therapeutic contexts

  • In silico biophysical property assessment

  • Sample-efficient experimental validation strategies

• Advanced imaging applications:

  • Super-resolution microscopy with specialized STRN antibodies

  • Intrabody development for live-cell tracking

  • Correlative light and electron microscopy for ultrastructural localization

• Therapeutic targeting strategies:

  • Development of antibody-drug conjugates targeting STRN in cancer contexts

  • Proteolysis targeting chimeras (PROTACs) guided by STRN antibody binding data

  • Computational design of high-affinity, high-specificity inhibitors

What methodological advances would improve the study of STRN in disease models?

Methodological innovations needed:

• CRISPR-based approaches:

  • Domain-specific knockin/knockout models

  • Endogenous tagging for improved antibody detection

  • Cell type-specific STRN manipulation in complex tissues

• Patient-derived models:

  • Organoid cultures with STRN antibody-based characterization

  • Correlation of STRN expression patterns with clinical outcomes

  • Ex vivo assessment of STRN-targeting therapeutics

• Multi-omics integration:

  • Correlation of STRN antibody-based proteomics with transcriptomics/genomics

  • Systems biology approaches to understand STRN network effects

  • Computational modeling of STRN interaction dynamics

• Longitudinal imaging:

  • In vivo imaging with STRN-targeted probes

  • Dynamic assessment of STRN expression during disease progression

  • Therapeutic response monitoring in preclinical models

How can researchers effectively validate novel STRN antibodies for emerging applications?

Comprehensive validation approaches:

• Cross-platform validation strategy:

  • Multi-application testing (WB, IHC, IF, IP, ELISA)

  • Cross-species reactivity assessment

  • Comparison against established antibody standards

• Genetic validation:

  • CRISPR knockout controls

  • siRNA knockdown (as established in published protocols)

  • Rescue experiments with STRN variants

• Epitope mapping:

  • Peptide arrays to determine precise binding sites

  • Competition assays between different STRN antibodies

  • Structural studies of antibody-antigen complexes

• Functional validation:

  • Assessment of ability to detect functional changes in STRN-dependent processes

  • Validation in disease-relevant contexts

  • Confirmation of ability to distinguish between STRN family members

• Reproducibility assessment:

  • Inter-laboratory validation

  • Batch-to-batch consistency testing

  • Documentation of validation data in public repositories