Phospho-SRF (S77) Antibody

What is Phospho-SRF (S77) Antibody and what does it specifically detect?

Phospho-SRF (S77) Antibody is a rabbit polyclonal antibody specifically designed to detect serum response factor (SRF) protein only when it's phosphorylated at the Serine 77 position. It recognizes the phosphorylated form of SRF by binding to a specific epitope around the phosphorylation site of S77. This antibody does not recognize non-phosphorylated SRF, making it valuable for studying SRF activation status in various cellular contexts .

What species does Phospho-SRF (S77) Antibody react with?

The Phospho-SRF (S77) Antibody shows reactivity with human and mouse samples as confirmed by multiple manufacturers . Some commercially available versions, such as the one from Affinity Biosciences (catalog #AF3727), also demonstrate reactivity with rat samples . This cross-species reactivity makes the antibody valuable for comparative studies across different mammalian model systems.

What are the common applications for Phospho-SRF (S77) Antibody?

Phospho-SRF (S77) Antibody can be utilized in multiple experimental applications including:

• Western Blot (WB) at dilutions of 1:500-1:2000

• Immunohistochemistry (IHC) at dilutions of 1:100-1:300

• Enzyme-Linked Immunosorbent Assay (ELISA) at a dilution of 1:40000

• Immunofluorescence (IF) at dilutions of 1:50-200

These applications enable researchers to detect phosphorylated SRF in various experimental contexts, from protein expression levels to cellular localization studies.

What is the recommended storage condition for Phospho-SRF (S77) Antibody?

Upon receipt, Phospho-SRF (S77) Antibody should be stored at -20°C or -80°C to maintain its activity and specificity. Repeated freeze-thaw cycles should be avoided as they can compromise antibody performance . The antibody is typically supplied in a storage buffer containing PBS with 50% glycerol, 0.5% BSA, and 0.02% sodium azide, which helps maintain stability during storage .

How does SRF phosphorylation at Serine 77 affect its function in gene regulation?

SRF functions as a transcription factor that binds to the serum response element (SRE), which is a short sequence of dyad symmetry located approximately 300 bp upstream of the transcription initiation site of certain genes (such as FOS). When phosphorylated at Serine 77, SRF's activity is modified, affecting its role in controlling expression of genes that regulate cytoskeletal dynamics, cell migration, and cardiac differentiation .

Phosphorylation of SRF at Ser77 is part of the regulatory mechanism that couples cytoskeletal gene expression to Rho GTPase-induced changes in cellular globular actin (G-actin) concentration. This phosphorylation event is critical for the SRF-MRTFA complex activity, which responds to cytoskeletal dynamics, thereby influencing development and morphogenesis processes .

What experimental controls should be included when using Phospho-SRF (S77) Antibody?

When using Phospho-SRF (S77) Antibody in experimental procedures, several controls should be included:

• Positive control: Samples known to contain phosphorylated SRF at Ser77, such as serum-stimulated cell lines

• Negative control: Samples treated with phosphatase to remove phosphorylation

• Peptide competition assay: Pre-incubation of the antibody with the phosphorylated peptide immunogen to verify specificity

• Non-phosphorylated control: Using a total SRF antibody in parallel to compare total vs. phosphorylated protein levels

• Knockout/knockdown validation: Using SRF-deficient samples to confirm specificity

These controls help ensure the validity of results and confirm the specificity of the antibody for the phosphorylated form of SRF.

How can Phospho-SRF (S77) Antibody be used to study SRF's role in cardiac differentiation?

Phospho-SRF (S77) Antibody can be employed in several methodological approaches to study SRF's role in cardiac differentiation:

• Temporal analysis: Tracking SRF phosphorylation status throughout cardiac differentiation using Western blot or immunofluorescence

• Co-localization studies: Combining Phospho-SRF (S77) Antibody with cardiac-specific markers in immunofluorescence experiments

• ChIP assays: Using the antibody to identify phospho-SRF-bound genomic regions during differentiation

• Phosphorylation dynamics: Comparing phosphorylation levels before and after treatment with cardiac differentiation inducing factors

• Mutation analysis: Comparing wild-type SRF to S77A mutants (preventing phosphorylation) to assess functional importance

These approaches can reveal how SRF phosphorylation contributes to cardiac differentiation and maturation processes.

What is the recommended protocol for Western blot using Phospho-SRF (S77) Antibody?

Western Blot Protocol for Phospho-SRF (S77) Antibody:

• Sample preparation:

  • Lyse cells in buffer containing phosphatase inhibitors

  • Denature proteins at 95°C for 5 minutes in loading buffer

  • Load 10-30 μg of protein per lane

• Electrophoresis and transfer:

  • Separate proteins using 10% SDS-PAGE (SRF has a calculated molecular weight of 52 kDa)

  • Transfer to PVDF or nitrocellulose membrane

• Immunoblotting:

  • Block in 5% BSA in TBST for 1 hour at room temperature

  • Incubate with Phospho-SRF (S77) Antibody at 1:500-1:2000 dilution in blocking buffer overnight at 4°C

  • Wash 3x with TBST

  • Incubate with appropriate HRP-conjugated secondary antibody

  • Wash 3x with TBST

  • Develop using ECL reagent and capture image

This protocol enables specific detection of phosphorylated SRF at Ser77 in protein samples, with expected band size of approximately 52 kDa.

What are the best practices for immunohistochemistry using Phospho-SRF (S77) Antibody?

Immunohistochemistry Protocol for Phospho-SRF (S77) Antibody:

• Sample preparation:

  • Fix tissue in 4% paraformaldehyde

  • Embed in paraffin and section (4-6 μm thickness), or prepare frozen sections

• Antigen retrieval:

  • For paraffin sections: Perform heat-induced epitope retrieval using citrate buffer (pH 6.0)

  • For frozen sections: Fix in acetone for 10 minutes at -20°C

• Staining procedure:

  • Block endogenous peroxidase with 3% H₂O₂

  • Block non-specific binding with 5% normal serum

  • Incubate with Phospho-SRF (S77) Antibody at 1:100-1:300 dilution overnight at 4°C

  • Wash 3x with PBS

  • Incubate with appropriate HRP-conjugated secondary antibody

  • Develop with DAB substrate

  • Counterstain with hematoxylin

  • Mount and visualize

This protocol allows for detection of phosphorylated SRF in tissue sections while preserving morphological context.

How should Phospho-SRF (S77) Antibody be optimized for immunofluorescence applications?

Immunofluorescence Optimization Protocol:

• Sample preparation:

  • Culture cells on coverslips or prepare tissue sections

  • Fix with 4% paraformaldehyde for 15 minutes at room temperature

• Optimization steps:

  • Test multiple dilutions (starting range: 1:50-1:200)

  • Compare different fixation methods (PFA vs. methanol)

  • Evaluate various blocking reagents (BSA, normal serum, commercial blockers)

  • Test different antigen retrieval methods if necessary

  • Optimize incubation times and temperatures

• Recommended procedure:

  • Permeabilize with 0.2% Triton X-100 for 10 minutes

  • Block with 3% BSA in PBS for 1 hour

  • Incubate with Phospho-SRF (S77) Antibody at optimized dilution overnight at 4°C

  • Wash 3x with PBS

  • Incubate with fluorophore-conjugated secondary antibody

  • Counterstain nuclei with DAPI

  • Mount and visualize by confocal microscopy

A titration experiment testing different antibody dilutions is crucial to determine the optimal signal-to-noise ratio for each specific experimental condition.

What are common issues encountered with Phospho-SRF (S77) Antibody and how can they be resolved?

Common Issues and Solutions:

These troubleshooting approaches can help researchers obtain reliable and consistent results when working with Phospho-SRF (S77) Antibody .

How can researchers distinguish between specific and non-specific signals when using Phospho-SRF (S77) Antibody?

To distinguish between specific and non-specific signals, researchers should:

• Run appropriate controls:

  • Include positive control samples (serum-stimulated cells)

  • Include negative control samples (phosphatase-treated or SRF-knockdown)

  • Perform peptide competition assays

• Validate with alternative methods:

  • Confirm phosphorylation with mass spectrometry

  • Use alternative phospho-specific antibodies

  • Correlate with kinase activity assays

• Consider experimental design:

  • Compare results with total SRF antibody

  • Examine expected molecular weight (52 kDa)

  • Evaluate subcellular localization (SRF is primarily nuclear)

  • Compare signal intensity with known biological stimuli that induce SRF phosphorylation

These approaches help ensure that observed signals truly represent phosphorylated SRF rather than non-specific antibody binding.

How should phosphorylation-specific data be normalized and quantified?

Data Normalization and Quantification Strategies:

• Western blot quantification:

  • Normalize phospho-SRF signal to total SRF levels from parallel blots

  • Use loading controls (β-actin, GAPDH) as secondary normalization

  • Present data as phospho-SRF/total SRF ratio

• Immunofluorescence quantification:

  • Measure nuclear fluorescence intensity

  • Normalize to DAPI or total SRF staining

  • Analyze multiple cells (>50) per condition

  • Use automated image analysis software for unbiased quantification

• Statistical considerations:

  • Perform at least three independent biological replicates

  • Apply appropriate statistical tests (t-test, ANOVA)

  • Consider variation in baseline phosphorylation levels

  • Account for exposure time differences between experiments

• Documentation:

  • Report exact normalization method in publications

  • Include representative images showing range of signals

  • Provide quantification graphs with error bars

  • Document image acquisition parameters

Proper normalization is critical for accurately interpreting changes in SRF phosphorylation status across different experimental conditions.

How can Phospho-SRF (S77) Antibody be used in ChIP-seq experiments to study SRF binding dynamics?

Chromatin Immunoprecipitation sequencing (ChIP-seq) using Phospho-SRF (S77) Antibody can provide valuable insights into how phosphorylation affects SRF genomic binding patterns:

• Experimental design:

  • Compare phospho-SRF ChIP-seq with total SRF ChIP-seq

  • Include stimulus conditions known to affect SRF phosphorylation

  • Use appropriate controls (input DNA, IgG control)

• Protocol modifications:

  • Increase antibody amount (4-10 μg per ChIP reaction)

  • Extend incubation time (overnight at 4°C)

  • Use protein A/G beads for rabbit IgG capture

  • Include phosphatase inhibitors in all buffers

• Data analysis:

  • Identify phospho-SRF-specific binding sites

  • Compare with known SRF binding motifs

  • Correlate with gene expression data

  • Analyze co-factors that may interact with phosphorylated SRF

This approach can reveal how phosphorylation at Ser77 influences SRF's ability to bind DNA and regulate target genes in different cellular contexts.

What is the relationship between SRF phosphorylation at Ser77 and its interaction with MRTFA in cytoskeletal gene regulation?

SRF functions with MRTFA (Myocardin-Related Transcription Factor A) to control expression of genes regulating the cytoskeleton during development, morphogenesis, and cell migration. The phosphorylation status of SRF at Ser77 significantly impacts this interaction:

• Functional relationship:

  • Phosphorylation at Ser77 can modulate the binding affinity between SRF and MRTFA

  • The SRF-MRTFA complex activity responds to Rho GTPase-induced changes in cellular G-actin concentration

  • This coupling mechanism connects cytoskeletal gene expression to cytoskeletal dynamics

• Experimental approaches to study this relationship:

  • Co-immunoprecipitation with Phospho-SRF (S77) Antibody to isolate MRTFA complexes

  • Proximity ligation assay to visualize interactions in situ

  • FRET analysis using tagged proteins to measure interaction dynamics

  • ChIP-reChIP to identify genomic regions bound by both phospho-SRF and MRTFA

These studies can illuminate how phosphorylation serves as a regulatory switch in controlling cytoskeletal gene expression through the SRF-MRTFA pathway.

How does SRF phosphorylation at Ser77 contribute to cardiac differentiation and maturation?

SRF is required for cardiac differentiation and maturation, and phosphorylation at Ser77 plays a regulatory role in these processes:

• Developmental significance:

  • Phosphorylation status changes during cardiomyocyte differentiation

  • Phospho-SRF may regulate a subset of cardiac-specific genes

  • The timing of phosphorylation correlates with critical developmental transitions

• Methodological approaches:

  • Temporal analysis of phospho-SRF levels during cardiac differentiation of stem cells

  • Comparison of wild-type vs. S77A mutant SRF in rescue experiments

  • Integration of phospho-SRF ChIP-seq with cardiac transcriptome data

  • Spatial mapping of phospho-SRF in developing cardiac tissue using the antibody

• Functional studies:

  • Analyzing the effects of kinase inhibitors that prevent Ser77 phosphorylation

  • Creating phosphomimetic (S77D) or phospho-null (S77A) SRF constructs

  • Examining downstream target gene expression in response to phosphorylation changes

Understanding the role of SRF phosphorylation in cardiac development could provide insights into congenital heart defects and cardiac regeneration strategies.