Phospho-STAT2 (Y631) Antibody

Fundamental Characteristics of Phospho-STAT2 (Y631) Antibody

Phospho-STAT2 (Y631) Antibody is a polyclonal antibody developed to specifically recognize STAT2 protein only when phosphorylated at the tyrosine 631 residue. This site-specific recognition capability makes it invaluable for studying signal transduction mechanisms involving STAT2 activation. The antibody is derived from rabbit hosts and demonstrates high specificity with no cross-reactivity with other proteins or non-phosphorylated STAT2 .

These antibodies are typically produced by immunizing rabbits with synthetic peptides derived from human STAT2 protein sequences surrounding the phosphorylation site of tyrosine 631. The resulting antiserum undergoes affinity purification using epitope-specific immunogens to ensure high specificity and reduced background noise in experimental applications. The amino acid range covered by the immunogen typically spans residues 597-646 or 570-650, depending on the manufacturer .

The physical and biochemical properties of commercially available Phospho-STAT2 (Y631) antibodies include liquid formulations in phosphate-buffered saline (PBS) containing preservatives and stabilizers such as glycerol, bovine serum albumin (BSA), and sodium azide. The concentration is typically standardized at 1 mg/ml, making it convenient for laboratory use across various applications .

Applications and Experimental Utilities

Phospho-STAT2 (Y631) Antibody has been validated for multiple experimental applications, making it a versatile tool in molecular and cellular biology research. Each application requires specific optimization conditions to achieve reliable and reproducible results.

Validated Applications

The antibody has been rigorously tested and validated for several experimental techniques, with recommended dilution factors established for optimal performance.

These recommended dilutions serve as starting points for assay optimization. The actual working concentration may vary depending on specific experimental conditions, sample types, and detection methods employed. Researchers are advised to perform titration experiments to determine the optimal antibody concentration for their specific applications .

Experimental Considerations

When working with Phospho-STAT2 (Y631) Antibody, several experimental considerations should be taken into account to ensure reliable results. The phosphorylation state of proteins can be labile and sensitive to sample preparation methods. Therefore, proper sample handling, including the use of phosphatase inhibitors during protein extraction, is essential to preserve the phosphorylation status of STAT2 at tyrosine 631.

For immunohistochemistry applications, appropriate antigen retrieval methods may be necessary to expose the phospho-epitope. The choice between heat-induced epitope retrieval (HIER) and enzymatic antigen retrieval should be empirically determined for each tissue type and fixation method. Additionally, blocking endogenous peroxidase activity and preventing non-specific binding are critical steps to minimize background staining and increase the signal-to-noise ratio .

In ELISA applications, the extraordinarily high dilution factor (1:40000) suggested for some commercial variants of this antibody indicates its high sensitivity and affinity for the phosphorylated epitope. This high sensitivity makes it particularly valuable for quantitative detection of phosphorylated STAT2 in complex biological samples .

Biological Significance of STAT2 and Y631 Phosphorylation

Understanding the biological significance of STAT2 and specifically the Y631 phosphorylation site provides important context for the utility of Phospho-STAT2 (Y631) Antibody in research applications. This knowledge helps researchers interpret experimental results and design appropriate studies.

STAT2 Structure and Function

STAT2 is a critical component of the interferon signaling pathway, functioning as a signal transducer and transcription factor. As a member of the STAT protein family, STAT2 plays a pivotal role in mediating cellular responses to cytokines and growth factors. The protein has a molecular weight of approximately 113 kDa and contains several functional domains including an SH2 domain, a DNA-binding domain, and transactivation domains .

In response to interferons (IFNs), particularly type I interferons like IFN-α and IFN-β, STAT2 becomes activated through phosphorylation. This activation prompts STAT2 to form a heterotrimeric complex with STAT1 and interferon regulatory factor 9 (IRF9, also known as p48 or ISGF3G). This complex, known as Interferon-Stimulated Gene Factor 3 (ISGF3), translocates to the nucleus where it binds to specific DNA sequences called Interferon-Stimulated Response Elements (ISREs) to initiate transcription of interferon-stimulated genes (ISGs) .

Unlike other STAT family members, STAT2 lacks direct DNA-binding capability. Instead, within the ISGF3 complex, STAT2 functions primarily as a transactivator, while STAT1 and IRF9 provide the DNA-binding functionality. This unique characteristic distinguishes STAT2 from other members of the STAT family and highlights its specialized role in interferon signaling .

Significance of Y631 Phosphorylation

The phosphorylation of STAT2 at tyrosine 631 (Y631) represents a critical regulatory mechanism in the interferon signaling pathway. This specific phosphorylation event is typically catalyzed by Janus kinases (JAKs) that are associated with interferon receptors. Upon interferon binding to its receptor, receptor-associated JAKs become activated and phosphorylate STAT2 at Y631, which is essential for subsequent STAT2 activation and function.

Y631 phosphorylation facilitates the interaction between STAT2 and STAT1, promoting heterodimer formation and subsequent assembly of the ISGF3 complex. This phosphorylation-dependent complex formation is a prerequisite for nuclear translocation and transcriptional regulation of interferon-responsive genes. Consequently, monitoring the phosphorylation status of STAT2 at Y631 using Phospho-STAT2 (Y631) Antibody provides valuable insights into the activation state of the interferon signaling pathway .

Research Applications and Significance

Phospho-STAT2 (Y631) Antibody has significant applications in various research fields, particularly in studies involving immune responses, viral infections, and inflammatory conditions. Its ability to specifically detect activated STAT2 makes it an invaluable tool for understanding signaling mechanisms and disease processes.

Immunological and Virological Research

In immunological research, this antibody allows scientists to monitor interferon signaling pathways that are critical for host defense against pathogens. By detecting phosphorylated STAT2, researchers can assess the activation status of the interferon response in various experimental conditions, including viral infections, autoimmune diseases, and inflammatory disorders.

The interferon pathway, in which STAT2 plays a crucial role, represents the first line of defense against viral infections. Many viruses have evolved mechanisms to inhibit this pathway, often targeting STAT2 function or its phosphorylation. Phospho-STAT2 (Y631) Antibody enables researchers to investigate these viral evasion strategies and understand how they impact interferon signaling and antiviral immunity .

Additionally, this antibody can be utilized to evaluate the efficacy of therapeutic agents designed to modulate the interferon response. Compounds that enhance or inhibit STAT2 phosphorylation can be screened and characterized using this antibody, facilitating drug discovery efforts aimed at treating viral infections, inflammatory diseases, and certain cancers where interferon signaling is implicated.

Molecular and Cellular Biology Applications

In molecular and cellular biology, Phospho-STAT2 (Y631) Antibody serves as a valuable tool for investigating signal transduction mechanisms. The antibody can be employed to track the spatiotemporal dynamics of STAT2 activation following stimulation with interferons or other cytokines, providing insights into the kinetics and regulation of this signaling pathway.

Furthermore, this antibody facilitates the study of protein-protein interactions involving phosphorylated STAT2. Co-immunoprecipitation experiments using Phospho-STAT2 (Y631) Antibody can identify novel interaction partners that specifically recognize the phosphorylated form of STAT2, expanding our understanding of the molecular mechanisms underlying interferon signaling.

The antibody also supports research on post-translational modifications beyond phosphorylation. The crosstalk between different modifications (such as phosphorylation, ubiquitination, SUMOylation, and acetylation) in regulating STAT2 function can be investigated using this antibody in combination with other modification-specific antibodies .

Quality Control and Validation

Quality control and validation procedures are essential aspects of antibody production and characterization, ensuring the reliability and reproducibility of experimental results obtained with Phospho-STAT2 (Y631) Antibody.

Validation Methodologies

Commercial suppliers of Phospho-STAT2 (Y631) Antibody implement rigorous validation protocols to confirm the specificity and sensitivity of their products. These validation procedures typically include multiple experimental approaches to verify that the antibody specifically recognizes phosphorylated STAT2 at tyrosine 631 without cross-reactivity to non-phosphorylated STAT2 or other phosphorylated proteins.

Validation methods commonly include Western blotting/immunoblotting with positive control samples (cells treated with interferon to induce STAT2 phosphorylation) and negative control samples (untreated cells or cells treated with phosphatase inhibitors). Additional validation approaches may involve immunohistochemistry, immunofluorescence, and ELISA using known positive and negative samples. Some manufacturers also perform phosphopeptide competition assays, where the antibody is pre-incubated with phosphorylated and non-phosphorylated peptides to confirm specificity for the phosphorylated form .

The absence of cross-reactivity with other proteins is an important quality attribute of Phospho-STAT2 (Y631) Antibody. Manufacturers verify this by testing the antibody against a panel of cell lysates or tissue samples expressing various proteins that might potentially cross-react with the antibody. The documented lack of cross-reactivity enhances the reliability of experimental results obtained with this antibody .

Performance Characteristics

The performance characteristics of Phospho-STAT2 (Y631) Antibody, including sensitivity, specificity, and reproducibility, determine its utility in various research applications. High sensitivity enables the detection of low levels of phosphorylated STAT2, which is particularly important when studying early events in signaling cascades or samples with limited amounts of target protein.

Specificity for the phosphorylated form of STAT2 is achieved through careful design of the immunogen and thorough purification procedures. The antibody specifically recognizes STAT2 when phosphorylated at tyrosine 631, without binding to non-phosphorylated STAT2 or other phosphorylated proteins. This high specificity minimizes false positive results and ensures accurate interpretation of experimental data .

Batch-to-batch reproducibility is maintained through standardized production processes and quality control measures. Each lot of antibody undergoes testing to verify consistent performance across multiple applications, ensuring that researchers can obtain reliable and reproducible results regardless of which batch they use .