Cleaved-CD97 (S531) Antibody

What is CD97 and what makes the cleaved form significant in research?

CD97, also known as ADGRE5 (adhesion G protein-coupled receptor E5), belongs to the EGF-TM7 subfamily of adhesion G protein-coupled receptors (aGPCRs). These receptors undergo self-catalytic proteolysis, resulting in a large extracellular subunit (α) and a seven-span transmembrane subunit (β) that associate at the cell surface as a receptor complex . The cleaved form is particularly significant because:

• The cleavage represents a functional activation mechanism for the receptor

• CD97 cleavage is implicated in tumorigenesis and cancer progression

• Cleaved CD97 fragments may serve as potential biomarkers in body fluids

• The cleavage process is essential for CD97's role in the immunological synapse

What is the structural significance of the S531 site in CD97β?

The S531 site represents a specific cleavage position adjacent to the GAIN (GPCR Autoproteolysis-INducing) domain of CD97. Antibodies targeting this specific site (such as Cleaved-CD97β (S531)) detect endogenous levels of activated CD97β protein fragments resulting from cleavage adjacent to this serine residue . Recent cryo-electron microscopy studies have revealed that:

• CD97 activation induces significant conformational changes in both extracellular and intracellular domains

• Cleavage creates larger cavities for Stachel sequence binding and G13 engagement

• The inactive form maintains a compact conformation with a constrained ligand pocket

What are the validated applications for Cleaved-CD97β (S531) antibodies?

Based on comprehensive testing, Cleaved-CD97β (S531) antibodies have been validated for the following applications:

The antibody specifically detects endogenous levels of activated CD97β protein resulting from cleavage adjacent to S531 . The antibody has not yet been extensively tested in all potential applications, so researchers should perform validation studies for novel applications.

How should researchers design experiments to study CD97 cleavage dynamics?

To effectively study CD97 cleavage dynamics, researchers should consider the following experimental design:

• Time course analysis: Monitor CD97 cleavage at multiple time points after stimulation to capture dynamics

• Subunit tracking: Use antibodies specific to both α and β subunits to track the fate of each subunit post-cleavage

• Soluble fragment detection: Implement appropriate techniques to capture released extracellular domains (sCD97)

• Controls: Include both negative controls (CD97-null cells) and positive controls (cells with known CD97 expression)

• Multiple detection methods: Combine flow cytometry (surface expression) with Western blotting (total protein levels)

Research has shown that detection of circulating sCD97 may require well-validated ELISAs, as inconsistent results have been reported when using non-validated assays .

How can Cleaved-CD97β (S531) antibodies contribute to cancer research?

CD97 has been implicated in multiple aspects of tumorigenesis, making the Cleaved-CD97β (S531) antibody valuable for cancer research:

• Tumor microenvironment analysis: CD97 is expressed on various immune cells infiltrating tumors

• Metastasis research: CD97 mediates processes closely related to tumor cell biology, including adhesion, detachment, migration, and polarity

• Biomarker development: Detecting cleaved CD97 fragments in patient samples may serve as potential biomarkers

• Therapeutic target validation: Studying CD97 activation mechanisms could inform development of antagonists for cancer therapy

Research protocols should incorporate:

• Comparative analysis between tumor tissue and adjacent normal tissue from the same patients

• Correlation of CD97 cleavage status with clinical parameters and patient outcomes

• Integration with other cancer markers for comprehensive tumor characterization

What is the role of CD97 cleavage in immunological synapse dynamics?

Recent research has demonstrated that CD97 localizes to and stabilizes the immunological synapse between dendritic cells and T cells. The cleaved form plays a crucial role in this process:

• CD97 contributes to dendritic cell-T cell interactions and T cell activation

• SteD (a Salmonella enterica effector) targets CD97 for degradation through ubiquitination

• Removal of CD97 by SteD inhibits dendritic cell-T cell interactions and reduces T cell activation

Experimental approaches to study this process should include:

• Co-culture systems with dendritic cells and T cells

• Live cell imaging to track CD97 localization at the immunological synapse

• Analysis of T cell activation markers in the presence or absence of functional CD97

• Mutation studies focused on the K555 ubiquitination site that affects CD97 degradation

How can researchers distinguish between intact and cleaved forms of CD97?

Distinguishing between intact and cleaved forms of CD97 requires careful experimental design:

• Antibody selection: Use antibodies that specifically recognize:

  • The CD97α subunit (suitable for flow cytometry)

  • The denatured CD97α or β subunits (suitable for immunoblotting)

  • The cleaved form at S531 (specific to cleaved product)

• Molecular weight analysis: Alternative splicing of CD97 mRNA generates at least three variants of the CD97α subunit (expected masses of 58 kDa, 48 kDa and 44 kDa), all interacting with the single variant of the CD97β subunit

• Validation controls:

  • Include both full-length and cleaved recombinant CD97 as controls

  • Use CD97 knockout/knockdown samples as negative controls

  • Compare with known CD97-expressing cell lines

What are the critical factors for reproducible detection of soluble CD97 (sCD97) in body fluids?

Detection of sCD97 in body fluids has shown inconsistent results in previous studies . To improve reliability:

• Sample handling protocols:

  • Process samples consistently to minimize pre-analytical variables

  • Consider appropriate protease inhibitors to prevent artificial degradation

  • Document freeze-thaw cycles as they may affect detection

• Assay validation:

  • Perform spike-and-recovery experiments to assess matrix effects

  • Conduct linearity-of-dilution tests with various body fluids

  • Validate antibody specificity using recombinant sCD97 standards

• Clinical correlation:

  • Document whether sCD97 detection relates to malignant tumors and/or inflammation

  • Compare results across different body fluids from the same patient

  • Establish robust cutoff values based on appropriate control populations

How might structural insights into CD97 activation inform development of targeted therapeutics?

Recent cryo-electron microscopy studies of human CD97 in both inactive apo and G13-bound fully active states have revealed important structural insights that may guide therapeutic development:

• Antagonist development: The compact inactive conformation of CD97 with a constrained ligand pocket provides structural information that could inform the design of antagonists

• Targeting activation mechanisms: Understanding the significant conformational changes that create larger cavities for Stachel sequence binding and G13 engagement could lead to modulators that specifically inhibit these transitions

• Experimental approaches:

  • Structure-based virtual screening for potential binding compounds

  • Functional assays measuring G-protein signaling in the presence of candidate molecules

  • Evaluation of compounds that stabilize inactive conformations versus those blocking active states

These structural insights will be particularly valuable for developing therapeutics targeting CD97 in diseases like cancer and immune and neurological disorders .

How does CD97-CD55 interaction influence immune function and tumor progression?

The interaction between CD97 and CD55 (decay-accelerating factor) has significant implications for both immune function and cancer biology:

• Immune regulation: The CD97-CD55 interaction has been convincingly shown to regulate immune functions, with recent scientific attention focused on this relationship

• Tumor relevance: CD97 and CD55 are co-expressed in several tumor entities, though the functional relevance of this relation has not been adequately clarified

• Research approaches:

  • Analysis of CD97 downregulation on circulating leukocytes by CD55

  • Investigation of whether homing/adhesion of circulating tumor cells can be mediated by CD97-CD55 interaction

  • Comparative studies of CD97-CD55 binding in immune versus tumor contexts

Future research should address whether the mechanisms promoting splenic dendritic cell homeostasis through CD97-CD55 interaction could similarly influence tumor cell behavior .