PRPF3 Antibody

What is PRPF3 and what is its function in cellular processes?

PRPF3 (PRP3 pre-mRNA processing factor 3 homolog) is a 77-78 kDa protein that functions as a critical component of the splicing machinery. It plays a role in pre-mRNA splicing as a component of the U4/U6-U5 tri-snRNP complex involved in spliceosome assembly and as a component of the precatalytic spliceosome (spliceosome B complex) . The U4/U6-associated splicing factor, Hprp3p, is homologous to yeast splicing factors and associates specifically with U4 and U6 snRNPs . PRPF3 is essential for the removal of introns from nuclear pre-mRNAs, a process that occurs on complexes called spliceosomes, which are made up of 4 small nuclear ribonucleoprotein (snRNP) particles and an undefined number of transiently associated splicing factors .

What are the typical applications for PRPF3 antibodies in research?

PRPF3 antibodies are commonly used in several experimental techniques:

• Western Blotting (WB): For detection of PRPF3 protein expression levels in various cell and tissue lysates, typically at dilutions ranging from 1:500-1:5000 .

• Immunohistochemistry (IHC): For localization of PRPF3 in tissue sections, with recommended dilutions of 1:30-1:500 depending on the antibody .

• Immunocytochemistry/Immunofluorescence (ICC/IF): For cellular localization studies, typically used at dilutions of 1:50-1:200 .

• Immunoprecipitation (IP): For isolation of PRPF3 protein complexes, with recommended amounts of 0.5-4.0 μg for 1.0-3.0 mg of total protein lysate .

These applications allow researchers to investigate PRPF3 expression, localization, and interaction partners in various experimental systems.

How do I optimize Western blot conditions for PRPF3 detection?

For optimal Western blot detection of PRPF3:

• Sample preparation: Use nuclear extracts or whole cell lysates depending on your research question, as PRPF3 is primarily localized to the nucleus .

• Protein loading: Load approximately 100 μg of total protein for tissue samples to ensure adequate detection .

• Expected molecular weight: While the calculated molecular weight of PRPF3 is approximately 78 kDa, observed molecular weights can vary between 78-90 kDa depending on the antibody and sample source .

• Antibody dilution: Begin with a 1:1000 dilution and optimize as needed based on signal intensity and background. Different antibodies may require different dilutions ranging from 1:500-1:5000 .

• Positive controls: Y79 cells, HepG2 cells, L02 cells, mouse brain tissue, and mouse liver tissue have been verified for positive PRPF3 detection .

Note that the observed band size might not always match the predicted molecular weight due to post-translational modifications, which can affect protein mobility in SDS-PAGE .

What are the key considerations for immunohistochemical detection of PRPF3?

For successful immunohistochemical detection of PRPF3:

• Antigen retrieval: Use TE buffer pH 9.0 or citrate buffer pH 6.0 depending on your tissue type and fixation method .

• Antibody dilution: Start with 1:100 dilution and adjust as needed, with recommended ranges typically between 1:50-1:500 .

• Validated tissue samples: Human stomach tissue and human liver cancer tissue have been successfully used for PRPF3 immunohistochemistry .

• Expected localization: PRPF3 should primarily localize to the nucleus and nuclear speckles as it colocalizes with spliceosomal snRNPs .

• Specificity controls: Include negative controls (primary antibody omission) and consider using tissues known to express different levels of PRPF3 as comparative references .

Remember that optimal conditions may vary depending on tissue type, fixation method, and the specific antibody being used.

How does PRPF3 expression vary across different tissues and developmental stages?

PRPF3 shows tissue-specific and developmental stage-dependent expression patterns:

• Temporal expression: Studies in mice have shown that PRPF3 mRNA levels in the retina are significantly higher than in brain tissue at 1 month, 4 months, and 1 year of age .

• Tissue distribution: While PRPF3 protein is expressed in all tissues, its level becomes particularly elevated in the retina compared to other tissues once mice reach adulthood (around 4 months) .

The table below summarizes PRPF3 mRNA levels in retina compared to brain tissue across different developmental stages:

Key: +: p<0.05; ++: p<0.01 (mRNA levels in retina significantly higher than brain); -: no difference

What is the subcellular localization of PRPF3 and how can it be visualized?

PRPF3 predominantly localizes to the nucleus, specifically in nuclear speckles where it colocalizes with spliceosomal snRNPs . This localization pattern is consistent with its function in pre-mRNA splicing.

To visualize PRPF3 subcellular localization:

• Immunofluorescence using fixed cells: PFA-fixed, Triton X-100 permeabilized cells can be stained with PRPF3 antibodies (typically at 2 μg/ml concentration) followed by fluorophore-conjugated secondary antibodies .

• Expression of tagged PRPF3: Studies have used HA-tagged human wild-type or mutant PRPF3 for localization studies, which showed that the majority of both wild-type and mutant PRPF3 proteins localize to the nucleus .

• Nuclear/cytoplasmic fractionation: While most PRPF3 is nuclear, some studies have detected a small fraction in the cytoplasm when overexpressed, which can be analyzed by subcellular fractionation followed by Western blotting .

For optimal imaging results, confocal microscopy is recommended to clearly visualize nuclear speckle patterns characteristic of splicing factors.

How are PRPF3 mutations associated with retinitis pigmentosa?

PRPF3 mutations have been identified in patients with autosomal dominant retinitis pigmentosa type 18 (RP18):

• Key mutations: Two single amino acid substitutions, Pro493Ser and Thr494Met, at the highly conserved PRPF3 C-terminal region are associated with RP18 .

• Mutation prevalence: Pro493Ser occurs sporadically, whereas Thr494Met is observed in several unlinked RP families worldwide, suggesting a potential hot spot at position 1482 of the PRPF3 gene .

• Disease phenotype: Thr494Met causes a mild late-onset and less severe RP phenotype compared to mutations in other splicing factors like PRPF31 and PRPC8 .

• Molecular mechanism: The Thr494Met mutation affects a potential recognition motif for phosphorylation by casein kinase II (CKII), as amino acids 494-497 (TKVE) of PRPF3 form a potential recognition site that is altered by the T494M mutation .

Interestingly, PRPF3 is highly expressed in photoreceptor cells of the retina, which may explain why mutations in this ubiquitously expressed splicing factor lead to retina-specific pathology .

How can PRPF3 antibodies be used to study retinitis pigmentosa models?

PRPF3 antibodies are valuable tools for studying retinitis pigmentosa models in several ways:

• Expression analysis: Western blotting can be used to compare PRPF3 protein levels between normal and diseased retinal tissues or in model systems expressing wild-type versus mutant PRPF3 .

• Localization studies: Immunohistochemistry and immunofluorescence can reveal whether disease-causing mutations alter the subcellular localization of PRPF3 in retinal cells .

• Protein-protein interactions: Immunoprecipitation with PRPF3 antibodies can identify changes in interaction partners caused by disease-associated mutations .

• In situ analysis: In situ hybridization for PRPF3 mRNA, complemented with immunohistochemistry for the protein, can reveal expression patterns in different retinal cell types .

Research has shown that PRPF3 mRNA is detected in all cellular layers of the retina with high levels in photoreceptor cells, confirming its importance in these specialized neurons .

How can PRPF3 knockdown and rescue experiments be designed using antibodies for validation?

For effective PRPF3 knockdown and rescue experiments:

• RNA interference: Small hairpin RNA (shRNA) can be used to specifically silence endogenous PRPF3 expression. Efficiency of knockdown should be validated by Western blot using PRPF3 antibodies .

• Rescue construct design: Express shRNA-resistant wild-type or mutant PRPF3 (e.g., with the Thr494Met mutation) that can be distinguished from endogenous protein using epitope tags (e.g., HA tag) .

• Validation strategy:

  • Confirm knockdown efficiency by Western blot (>90% knockdown is achievable)

  • Verify expression level of the rescue construct

  • Assess subcellular localization of expressed proteins by immunofluorescence

  • Evaluate functional rescue using appropriate splicing assays

• Important controls: Include empty vector controls and compare nuclear/cytoplasmic fractionation results between wild-type and mutant rescue constructs to detect any differences in localization or solubility .

In published studies, researchers have successfully achieved more than 90% knockdown of endogenous PRPF3 while simultaneously expressing HA-tagged human wild-type or Thr494Met PRPF3 using viral vectors .

What are the best approaches to study PRPF3 phosphorylation status?

To investigate PRPF3 phosphorylation:

• Phosphorylation-specific antibodies: Although not mentioned in the search results, phospho-specific antibodies could be developed targeting known phosphorylation sites, particularly the CKII recognition motif (TKVE) affected by the Thr494Met mutation .

• Phosphorylation detection methods:

  • Phos-tag SDS-PAGE followed by Western blotting with PRPF3 antibodies to separate phosphorylated from non-phosphorylated forms

  • Immunoprecipitation with PRPF3 antibodies followed by phosphorylation-specific staining or mass spectrometry

  • In vitro kinase assays using purified PRPF3 and candidate kinases like CKII

• Functional studies: Compare wild-type and phosphorylation site mutants (e.g., T494A to prevent phosphorylation) to determine the impact on:

  • Protein-protein interactions in the spliceosome

  • Splicing efficiency of reporter constructs

  • Cellular localization

Research has indicated that PRPF3 is phosphorylated, and the Thr494Met mutation associated with retinitis pigmentosa affects a potential CKII phosphorylation site, suggesting that altered phosphorylation may contribute to disease pathogenesis .

How do I address band size discrepancies in Western blots for PRPF3?

When encountering band size discrepancies in PRPF3 Western blots:

• Expected versus observed weights: PRPF3 has a calculated molecular weight of 78 kDa, but observed molecular weights can vary between 78-90 kDa .

• Potential causes of discrepancies:

  • Post-translational modifications, particularly phosphorylation

  • Alternative splicing variants

  • Sample preparation methods affecting protein mobility

  • Different protein denaturation conditions

• Validation approaches:

  • Use multiple antibodies targeting different epitopes of PRPF3

  • Include positive control samples with known PRPF3 expression (e.g., HepG2 cells, Y79 cells)

  • Perform immunoprecipitation followed by Western blotting to confirm specificity

  • Consider treating samples with phosphatases to determine if phosphorylation contributes to the size shift

As noted in the Elabscience antibody documentation: "The actual band is not consistent with the expectation. Western blotting is a method for detecting a certain protein in a complex sample based on the specific binding of antigen and antibody. Different proteins can be divided into bands based on different mobility rates. The mobility is affected by many factors, which may cause the observed band size to be inconsistent with the expected size."

What experimental controls should be included in PRPF3 antibody-based experiments?

For rigorous PRPF3 antibody-based experiments, include these controls:

• Positive controls:

  • Cell lines with known PRPF3 expression (HepG2, Y79, L02 cells)

  • Tissue samples with validated expression (mouse brain, mouse liver, human stomach)

  • Overexpression systems (PRPF3-transfected HEK-293T cells)

• Negative controls:

  • Primary antibody omission control

  • Non-specific IgG control for immunoprecipitation

  • Vector-only transfected cells for overexpression studies

  • Non-expressing tissues or knockdown samples when available

• Specificity controls:

  • Pre-adsorption with immunizing peptide when available

  • Comparison of multiple antibodies targeting different PRPF3 epitopes

  • Correlation of protein detection with mRNA expression data

  • Knockdown validation showing reduced signal

• For immunohistochemistry/immunofluorescence:

  • Include counterstains to verify nuclear localization (e.g., DAPI)

  • Compare with known nuclear speckle markers to confirm subcellular localization

Proper controls ensure reliable interpretation of results and help troubleshoot experimental issues when they arise.