RR3 Antibody

What is RR3 antibody and what epitopes does it recognize?

RR3 antibody appears in multiple research contexts. The Santa Cruz Biotechnology COX4I2 (RR3) Antibody (sc-100522) is a mouse IgG 2a κ monoclonal antibody that recognizes amino acids 21-105 of human COX4I2 . In immunology research, RR3 refers to a series of rat monoclonal antibodies (RR3-15, RR3-16, and RR3-18) that were established by fusing spleen cells from rats immunized with male antigen-specific cytolytic T cell clone OH6 to mouse myeloma cells . In plant science, RR3 antibodies specifically target rice proteins .

What applications are RR3 antibodies validated for?

RR3 antibodies demonstrate utility across multiple experimental techniques. The COX4I2 (RR3) antibody from Santa Cruz Biotechnology is validated for Western blot (WB), immunoprecipitation (IP), immunofluorescence (IF), immunohistochemistry on paraffin-embedded samples (IHC-P), and ELISA applications . Plant-specific RR3 antibodies from suppliers such as CUSABIO, Biorbyt, and MyBioSource are primarily validated for Western blot and ELISA techniques . The T-cell receptor-specific RR3 monoclonal antibodies were validated through immunoprecipitation studies, where each antibody successfully precipitated a 90 kDa disulfide-linked heterodimer characteristic of the TCR .

What species reactivity profiles do different RR3 antibodies exhibit?

The species reactivity of RR3 antibodies varies depending on the specific variant:

This diversity highlights the importance of selecting the appropriate RR3 antibody variant for your specific experimental system .

How is the RR3-16 antibody used in T cell research?

The RR3-16 monoclonal antibody has demonstrated particular value in T cell research. Surface immunofluorescence staining experiments revealed that RR3-16 reacts with both the OH6 T cell clone and a minor fraction of normal T cells. This reactivity was linked to the expression of a gene in the V alpha 3 family of T cell receptors . Notably, RR3-16 does not react with all T cell lines and clones known to express genes from the V alpha 3 family, indicating specificity for a single member of the TCR V alpha 3 gene family . This makes RR3-16 particularly valuable for studying specific T cell receptor variants.

What methodological considerations are important for Western blotting with RR3 antibodies?

For optimal Western blotting results with RR3 antibodies, researchers should implement the following protocol optimizations:

• Sample preparation: For COX4I2 detection, mitochondrial enrichment protocols improve signal detection. For plant samples, use extraction buffers containing protease inhibitors to prevent degradation.

• Electrophoresis conditions: Use reducing conditions with COX4I2 (RR3) antibody. The disulfide-linked heterodimer recognized by RR3 TCR antibodies requires careful consideration of reducing versus non-reducing conditions.

• Transfer parameters: Optimize transfer time and voltage based on protein size (COX4I2 is approximately 20 kDa; TCR heterodimers are approximately 90 kDa).

• Blocking and antibody dilution: Titrate antibody concentration starting from manufacturer recommendations (Santa Cruz COX4I2 RR3 antibody is supplied at 100 μg/ml).

• Detection methods: Choose chemiluminescence for highest sensitivity when working with low-abundance proteins like TCR variants .

What is the significance of RR3-16+ TCR preferential expression in CD8+ T cells?

Analysis of RR3-16+ TCR expression in CD4+ and CD8+ T cell subsets revealed a striking preferential expression on CD8+ T cells, suggesting regulated expression of this particular TCR V alpha gene . This finding has significant implications for understanding:

• T cell development and lineage commitment processes

• Potential role of specific TCR V alpha genes in cytotoxic T cell function

• Possible applications in tracking specific CD8+ T cell populations in immune responses

• Insights into how TCR gene expression may influence CD4/CD8 lineage decisions

The preferential expression pattern suggests that RR3-16 could serve as a valuable marker for studying specific cytotoxic T cell populations in various immunological contexts .

How can CRISPR/Cas9 technology complement RR3 antibody-based studies?

CRISPR/Cas9 technology offers powerful complementary approaches to antibody-based detection of proteins like COX4I2. Santa Cruz Biotechnology provides several CRISPR tools for COX4I2 research:

These tools enable researchers to:

• Generate knockout cell lines to validate antibody specificity

• Create cellular models to study protein function

• Introduce specific mutations to study structure-function relationships

• Upregulate protein expression for enhanced detection or functional studies

The combination of CRISPR genetic manipulation with RR3 antibody-based detection provides a comprehensive approach to protein characterization .

What controls are essential when using RR3 antibodies in immunohistochemistry or immunofluorescence?

For reliable results in immunohistochemistry or immunofluorescence experiments with RR3 antibodies, the following controls are essential:

• Negative controls:

  • Primary antibody omission

  • Isotype-matched irrelevant antibody (mouse IgG 2a κ for COX4I2 RR3)

  • Antigen-negative tissues/cells

• Positive controls:

  • Tissues/cells known to express the target (lung tissue is enriched for COX4I2)

  • Cell lines overexpressing the target protein

• Specificity controls:

  • CRISPR knockout samples

  • siRNA knockdown samples

  • Peptide competition/blocking experiments

• Co-localization controls:

  • For COX4I2, co-staining with mitochondrial markers

  • For TCR studies, co-staining with CD3 or other T cell markers

These controls ensure that staining patterns reflect true protein localization rather than technical artifacts .

How have computational approaches advanced antibody design for research applications?

Third-generation antibody discovery methods using in silico rational design represent a significant advancement in antibody technology. These computational approaches complement traditional in vivo and in vitro methods by:

• Enabling epitope mapping and accessibility prediction

• Modeling antibody-antigen interactions to optimize binding affinity

• Predicting potential cross-reactivity with related proteins

• Design of humanized antibodies with reduced immunogenicity

A method called "Modular" implements rational design of antibodies in a modular manner, offering significant opportunities for antibody engineering . For RR3 antibodies, computational approaches could theoretically improve:

• Specificity for distinguishing between closely related TCR V alpha family members

• Binding affinity for enhanced detection of low-abundance targets

• Performance in challenging applications like live-cell imaging

These advances highlight how computational tools are transforming antibody development beyond traditional hybridoma technology .

What mechanisms explain the specificity of RR3-16 for a single member of the TCR V alpha 3 gene family?

The remarkable specificity of RR3-16 for a single member of the TCR V alpha 3 gene family can be explained through molecular characterization studies. cDNA sequence analysis of three independent RR3-16+ T cell hybridomas using polymerase chain reaction revealed sequences identical to the previously published V alpha 3 sequence of the CTL clone C9 . This suggests that RR3-16 recognizes a unique epitope configuration present in only this particular V alpha 3 variant.

Several mechanisms may contribute to this specificity:

• Recognition of specific amino acid residues in complementarity-determining regions (CDRs)

• Conformation-dependent epitope formed by the three-dimensional folding of the protein

• Possible recognition of a junction region between V alpha 3 and joining segments

• Potential involvement of post-translational modifications specific to this TCR variant

This level of specificity makes RR3-16 an exceptionally valuable reagent for studying TCR diversity and T cell subset distribution .