CADM4 Antibody

What applications are validated for CADM4 antibodies?

CADM4 antibodies have been successfully validated for multiple research applications, with varying detection sensitivities:

For optimal results, verification of antibody reactivity with your specific sample type is recommended. Multiple studies have demonstrated successful application of CADM4 antibodies in human, mouse, and rat samples . The observed molecular weight of CADM4 typically ranges between 60-70 kDa on Western blots, despite the calculated molecular weight of approximately 43 kDa, likely due to post-translational modifications .

What is the significance of epitope selection for CADM4 antibodies?

The selection of target epitopes significantly impacts the utility of CADM4 antibodies in specific research applications:

When studying CADM4 palmitoylation, antibodies targeting the C-terminal region are particularly useful, as this region contains the critical cysteine-347 residue that undergoes palmitoylation . For applications requiring distinction between wild-type and mutant CADM4, using antibodies targeting specific domains can be crucial. For example, in studies involving Cadm4dCT (deletion of cytoplasmic domain), antibodies directed to the cytoplasmic domain will only detect the endogenous protein .

What are the recommended storage conditions for CADM4 antibodies?

To maintain optimal antibody activity and prevent degradation:

Most commercially available CADM4 antibodies are supplied in a storage buffer containing PBS with sodium azide and glycerol, which helps maintain stability during freeze-thaw cycles . For long-term storage beyond one year, validation of antibody performance before use is recommended to ensure specificity and sensitivity have not diminished.

How can CADM4 antibodies be utilized to investigate the role of palmitoylation in protein function?

Investigating CADM4 palmitoylation requires specialized techniques combining antibody-based detection with palmitoylation-specific assays:

• Acyl-RAC Assay with CADM4 Antibodies:

  • This method allows detection of palmitoylated CADM4 by replacing the palmitoyl moiety with a biotinylated group

  • Subsequent detection with CADM4 antibodies can confirm palmitoylation status

  • Has been successfully used to demonstrate that C347 is the major palmitoylation site in CADM4

• mPEG Labeling Combined with Western Blotting:

  • mPEG substitutes palmitate on CADM4, causing a detectable band shift on Western blots

  • CADM4 antibodies can then detect both modified and unmodified forms

  • Research has shown this technique can distinguish between wild-type CADM4 (showing a migrated band) and C347A mutants (showing no migration)

• Pharmacological Inhibition Studies:

  • Treatment with palmitoylation inhibitors like 2-BP (2-bromopalmitate)

  • Western blotting with CADM4 antibodies to detect changes in plasma membrane localization

  • Studies have shown that both C347A mutation and 2-BP treatment result in decreased plasma membrane localization of CADM4

These techniques have revealed that palmitoylation at C347 is crucial for CADM4 stability on the plasma membrane, and its disruption leads to protein internalization and subsequent degradation through the autophagy-lysosome pathway .

What methodological approaches are recommended for using CADM4 antibodies in neurological disease research?

CADM4 plays critical roles in myelination processes, with significant implications for neurological disorders:

When investigating demyelination diseases:

• Tissue-specific localization studies:

  • Combine CADM4 antibodies with markers for neurons (e.g., NeuN), oligodendrocytes (e.g., CC1), and myelin (e.g., MBP)

  • This approach has demonstrated that Cadm4-KI mice show dramatic decrease in MBP expression, explaining the downregulation of myelination

• Ultrastructural analysis:

  • Combine electron microscopy with immunogold labeling using CADM4 antibodies

  • Allows visualization of precise subcellular localization and calculation of g-ratio values

  • Research has shown that Cadm4-KI mice exhibit reduced g-ratio values compared to wild-type, indicating thickened myelin sheaths

• Functional correlations:

  • Correlate CADM4 expression levels with behavioral assessments (e.g., rotarod performance)

  • Studies have shown that Cadm4-KI mice display hind leg rigidity and enhanced clasping reflex, indicating functional consequences of CADM4 dysfunction

Recent research has identified the ZDHHC3-Cadm4 palmitoylation axis as crucial for CNS myelination, suggesting a potential therapeutic target for demyelination disorders .

What are the considerations for validating CADM4 antibody specificity in experimental designs?

Thorough validation is critical to ensure reliable and reproducible results:

• Genetic validation approaches:

  • Use of Cadm4-knockout mouse models as negative controls

  • Studies have validated antibody specificity using teased fiber preparations from Cadm4−/− mice

  • Consider cross-reactivity with other CADM family members (CADM1-3) due to sequence homology

• Recombinant protein controls:

  • Test against recombinant CADM4 and related proteins

  • Some antibodies show no cross-reactivity with rhIGSF4A, rhIGSF4B, rhIGSF4D, or rhIGSF8 in direct ELISAs and Western blots

• Immunogen consideration:

  • Verify the immunogen sequence used for antibody generation

  • Antibodies generated against different regions (e.g., AA 141-240 vs. C-terminal) may yield different results

  • C-terminal antibodies are particularly important for distinguishing endogenous from truncated forms

• Application-specific validation:

  • For IHC studies, include tissue arrays of multiple human tissues

  • For protein interaction studies, validate with protein arrays of human recombinant protein fragments

  • Some commercial antibodies have been tested on arrays of 44 normal human tissues and 20 common cancer types

When studying neuron-glia interactions, it's particularly important to validate specificity, as demonstrated in studies where CADM4 antibody reactivity was tested in various experimental conditions, including OLs grown alone, on nanofibers, or with neurons from mice lacking axonal receptors of CADM4 .

How can CADM4 antibodies be utilized to investigate its role as a tumor suppressor?

CADM4 has emerging roles in cancer biology that can be investigated through specific antibody applications:

These methodological approaches have established CADM4 as an independent prognostic factor in gallbladder cancer (p = 0.013 in multivariate analyses) , suggesting its potential utility as a prognostic biomarker in clinical settings.

What experimental approaches are recommended for investigating CADM4's role in axon-glia interactions?

Investigating CADM4's function in neuron-glial communication requires specialized experimental designs:

• Co-culture systems with differential antibody labeling:

  • Culture oligodendrocytes expressing wild-type or mutant CADM4 with neurons

  • Use combinatorial immunolabeling with CADM4 antibodies and neuronal markers

  • Studies revealed that Cadm4dCT-expressing oligodendrocytes form excessive axon-glia contacts that fail to elongate into mature myelin

• Transgenic models with tissue-specific expression:

  • Analyze transgenic mice expressing mutant forms of CADM4 under cell-specific promoters

  • Combined with immunolabeling for myelin and nodal markers

  • Research with Tg(mbp-Cadm4dCT) mice demonstrated that altered CADM4 function leads to hypomyelination and myelination of neuronal somata

• Specificity control experiments:

  • Compare CADM4 antibody staining patterns in OLs grown:
    a) Alone
    b) On nanofibers
    c) With neurons
    d) With neurons lacking CADM4 receptors

  • Such approaches confirmed that abnormalities in Tg(mbp-Cadm4dCT) mice were dependent on neuron-glia adhesion mediated by CADM4