SF3A3 Antibody

What is SF3A3 and what is its role in cellular processes?

SF3A3 (Splicing Factor 3a Subunit 3), also known as SAP61 or SF3a60, is a critical 60kDa component of the 17S U2 snRNP complex in the spliceosome. This protein plays an essential role in pre-mRNA splicing by:

• Directly participating in early spliceosome assembly

• Contributing to the conversion of 15S U2 snRNP into an active 17S particle

• Mediating recognition of the intron branch site during pre-mRNA splicing

• Promoting selection of the pre-mRNA branch-site adenosine (the nucleophile for the first step of splicing)

Within the spliceosome, SF3A3 functions as part of the SF3A subcomplex that contributes to the assembly of both the pre-spliceosome 'E' complex and the pre-catalytic spliceosome 'A' complex . Research has shown that the zinc finger domain of SF3A3 plays a specific role in its binding to the 15S U2 snRNP .

What experimental applications are SF3A3 antibodies validated for?

SF3A3 antibodies are validated for multiple research applications with specific optimization parameters:

Most commercial antibodies show reactivity with human, mouse, and rat samples, with predicted reactivity for additional species including bovine, pig, dog, and others based on sequence homology .

What are the recommended protocols for Western blot detection of SF3A3?

For optimal SF3A3 detection by Western blotting, researchers should follow these methodological guidelines:

• Sample preparation:

  • Extract proteins using RIPA Lysis Buffer containing 1% phenylmethylsulphonyl fluoride (PMSF)

  • Measure protein concentration with BCA protein assay kit

  • Denature proteins at 100°C for 8 min with Protein Loading Buffer

• Gel electrophoresis and transfer:

  • Separate on 10% sodium dodecyl sulfate–polyacrylamide gel (SDS-PAGE)

  • Transfer onto PVDF membranes

  • Block membranes for 20 min in quick blocking solution at room temperature

• Antibody incubation:

  • Incubate with primary SF3A3 antibody (typically 1:1000 dilution) overnight at 4°C with gentle shaking

  • Wash thoroughly

  • Incubate with appropriate HRP-conjugated secondary antibody

• Detection:

  • Look for SF3A3 band at approximately 59-62 kDa

  • Verify specificity by comparing with positive control cell lines (A431, Raji, A549, K-562, or NIH/3T3 cells)

How can SF3A3 antibodies be utilized to study protein-protein interactions in the spliceosome?

Investigating SF3A3's interactions with other spliceosomal components requires sophisticated methodological approaches:

• Co-Immunoprecipitation (Co-IP):

  • Utilize SF3A3 antibodies (typically at IP dilution of 1:50) to precipitate SF3A3 complexes

  • Analyze interacting partners by Western blotting

  • Validated antibodies from Cell Signaling Technology and Proteintech have been successfully used for IP applications

• RNA Immunoprecipitation (RIP):

  • Use commercial RIP kits with SF3A3 antibodies to isolate SF3A3-RNA complexes

  • Compare results with IgG negative controls

  • This approach has been used to identify SF3A3 interactions with specific RNAs including U2 snRNA

• Immunoprecipitation with ubiquitination analysis:

  • Incubate lysates with SF3A3 antibodies and protein A/G magnetic beads

  • Wash beads thoroughly before immunoblotting with ubiquitin antibodies

  • This method has revealed mechanisms of SF3A3 regulation through ubiquitin-proteasome-mediated degradation

What evidence exists for SF3A3's involvement in cancer progression?

Recent research has uncovered significant roles for SF3A3 in cancer development and progression:

• Breast cancer:

  • SF3A3 protein levels are rapidly upregulated in human primary mammary epithelial cells upon MYC hyperactivation

  • Elevated SF3A3 levels are observed in triple-negative breast cancer (TNBC) cell lines with MYC amplification/overexpression

  • SF3A3 protein levels predict molecular and phenotypic features of aggressive human breast cancers

• Lung cancer:

  • CircSCAP directly binds to SF3A3 protein, facilitating the reduction of SF3A3 by promoting its ubiquitin-proteasome-mediated degradation

  • This interaction enhances MDM4-S expression, ultimately activating p53 signaling

  • Research has identified a novel circSCAP/SF3A3/p53 signaling axis involved in suppressing the malignancy of non-small cell lung cancer (NSCLC)

• Mechanistic insights:

  • SF3A3 levels are modulated translationally through an RNA stem-loop in an eIF3D-dependent manner upon MYC hyperactivation

  • This regulation ensures accurate splicing of mRNAs enriched for mitochondrial regulators

  • Altered SF3A3 translation leads to metabolic reprogramming and stem-like properties that fuel MYC tumorigenic potential in vivo

How can researchers investigate SF3A3's role in alternative splicing mechanisms?

To explore SF3A3's functions in splicing regulation, researchers should consider these methodological approaches:

• Alternative splicing analysis after SF3A3 manipulation:

  • Utilize shRNA or siRNA-mediated knockdown of SF3A3

  • Analyze changes in splicing patterns using RNA-seq

  • Research has shown that SF3A3 depletion affects multiple types of alternative splicing events, including skipped exons (SE), mutually exclusive exons (MXE), alternative 3' splice sites (A3SS), alternative 5' splice sites (A5SS), and retained introns (RI)

• Quantitative assessment of splicing changes:

  • Calculate Percentage Spliced-In (PSI) values to quantify alterations in splicing patterns

  • Compare PSI values between control and SF3A3-depleted conditions

  • Studies have revealed significant changes in PSI values for numerous alternative splicing events following SF3A3 knockdown in the context of MYC activation

• Functional validation of SF3A3-dependent splicing events:

  • Identify specific splicing events regulated by SF3A3

  • Design primers to detect splice variants by RT-PCR

  • Perform rescue experiments with wildtype or mutant SF3A3 to confirm specificity

• p53 signaling activity assays:

  • Transfect cells with SF3A3 siRNA

  • Introduce p53-responsive luciferase reporters (such as pp53-TA-GLuc-Dura)

  • Measure luciferase activity with and without p53 inhibitors like pifithrin-α to validate specificity of the observed effects

What approaches should be used to validate SF3A3 antibody specificity?

Ensuring antibody specificity is crucial for generating reliable experimental results. For SF3A3 antibodies, researchers should implement multiple validation strategies:

• Western blot validation:

  • Confirm detection of a single band at the expected molecular weight (59-62 kDa)

  • Test across multiple cell types (A431, Raji, A549, K-562, NIH/3T3) to ensure consistent detection

  • Compare with known positive controls

• Knockdown/knockout controls:

  • Perform SF3A3 knockdown using validated shRNA or siRNA sequences

  • Confirm reduction in antibody signal proportional to knockdown efficiency

  • This approach provides the strongest evidence for antibody specificity

• Immunohistochemistry validation:

  • Include appropriate positive controls (such as human lung cancer tissue)

  • Perform antigen retrieval optimization (TE buffer pH 9.0 or citrate buffer pH 6.0)

  • Compare staining patterns with known subcellular localization

  • Validate with additional antibodies targeting different epitopes

• Immunoprecipitation validation:

  • Confirm pull-down of the correctly sized protein by Western blot

  • Verify identity of immunoprecipitated proteins using mass spectrometry

  • Compare results using different SF3A3 antibodies

How can SF3A3 antibodies be used to investigate its potential as a biomarker or therapeutic target?

Research indicates SF3A3 may have significant potential as both a biomarker and therapeutic target:

• Biomarker development approaches:

  • Perform immunohistochemical analysis of SF3A3 expression in tissue microarrays

  • Correlate expression levels with clinical parameters and patient outcomes

  • Research has shown that SF3A3 protein levels can predict features of aggressive human breast cancers

  • Studies indicate that patients with dysregulated SF3A3-related pathways have significantly poorer prognosis

• Therapeutic targeting strategies:

  • Investigate cellular responses to SF3A3 depletion in various cancer contexts

  • Research has shown that partial depletion of SF3A3 significantly reduces cell survival specifically upon oncogenic activation

  • This suggests SF3A3 targeting may provide a therapeutic window that preferentially affects cancer cells

• Metabolic reprogramming investigation:

  • Use SF3A3 antibodies to study how SF3A3 levels correlate with metabolic changes

  • Research indicates that SF3A3 regulates splicing of mRNAs enriched for mitochondrial regulators

  • This connection between SF3A3 and metabolism provides additional therapeutic avenues to explore