PPP1R9B Antibody

What is PPP1R9B and why is it important in neuroscience research?

PPP1R9B (Protein Phosphatase 1 Regulatory Subunit 9B), also known as Spinophilin or Neurabin-2, functions as a scaffold protein in multiple signaling pathways. It modulates excitatory synaptic transmission and dendritic spine morphology through its interaction with protein phosphatase 1 (PP1) and actin filaments . The protein is abundantly expressed in the brain, with highest levels detected in the hippocampus and lower levels in the cortex, cerebellum, and brainstem . PPP1R9B is particularly important in neuroscience research because it localizes to dendritic spines and plays critical roles in regulating synaptic plasticity and neuronal function. The dysregulation of PP1 activity, which PPP1R9B helps regulate, has been linked to various neurological disorders including Alzheimer's disease and schizophrenia, highlighting its potential as a therapeutic target .

How do I select the appropriate PPP1R9B antibody for my specific research application?

Selection of the appropriate PPP1R9B antibody should be based on several key considerations:

• Experimental application: Different antibodies are validated for specific applications. For example, from the search results:

  • For Western blot: Most antibodies are validated, with recommended dilutions ranging from 1:500-1:8000

  • For immunohistochemistry: Some antibodies (e.g., 55129-1-AP) are validated with recommended dilutions of 1:20-1:200

  • For immunoprecipitation: Specific antibodies like 55129-1-AP are recommended, with suggested amounts of 0.5-4.0 μg for 1.0-3.0 mg of total protein lysate

• Species reactivity: Confirm the antibody recognizes PPP1R9B from your experimental species. Common reactivities include:

  • Human and mouse (e.g., CAB17230)

  • Human, mouse, and rat (e.g., CAB17229)

• Epitope recognition: Consider the region of PPP1R9B recognized by the antibody. Many antibodies target a synthetic peptide corresponding to amino acids 250-350 of human PPP1R9B (NP_115984.3) , while others may target different regions.

• Validation data: Review the available validation data for your application and species of interest. For example, R&D Systems antibody AF6465 shows specific detection in human and rat brain tissues by Western blot and in rat hippocampal neurons by immunofluorescence .

What is the expected molecular weight of PPP1R9B in different experimental systems?

Although the calculated molecular weight of PPP1R9B is approximately 89 kDa , the observed molecular weight in experimental systems often differs:

This discrepancy between calculated and observed molecular weight is documented in multiple sources. For example, Proteintech's antibody datasheet notes that while the calculated molecular weight is 89 kDa, the observed molecular weight is typically 120-130 kDa . R&D Systems similarly reports that PPP1R9B is detected at approximately 90-120 kDa on Western blots . This higher-than-expected molecular weight is likely due to post-translational modifications and the protein's structure affecting its mobility in SDS-PAGE.

How should I optimize immunohistochemistry protocols for PPP1R9B detection in brain tissue?

Optimizing immunohistochemistry protocols for PPP1R9B detection in brain tissue requires careful consideration of several factors:

• Antigen retrieval method: For PPP1R9B detection in brain tissue, most protocols recommend:

  • Primary option: Antigen retrieval with TE buffer pH 9.0

  • Alternative option: Citrate buffer pH 6.0

• Antibody concentration: Begin with the manufacturer's recommended dilution range (e.g., 1:20-1:200 for IHC with antibody 55129-1-AP) and perform a titration experiment to determine the optimal concentration for your specific tissue.

• Incubation conditions: For optimal results when detecting PPP1R9B in neuronal tissues:

  • R&D Systems protocol used 10 μg/mL of their antibody (AF6465) for 3 hours at room temperature on fixed rat hippocampal neurons

  • For paraffin-embedded tissues, overnight incubation at 4°C is often recommended

• Detection system: For fluorescent detection in neurons, consider:

  • Primary antibody: Anti-PPP1R9B antibody

  • Secondary antibody: Species-appropriate fluorescently labeled secondary (e.g., NorthernLights™ 557-conjugated Anti-Sheep IgG for the AF6465 antibody)

  • Counter-staining: DAPI for nuclei visualization

  • Co-staining: Consider using neuron-specific markers such as beta-III Tubulin for contextual localization

• Controls: Include both positive controls (tissues known to express PPP1R9B, such as hippocampus) and negative controls (primary antibody omission) in each experiment.

Research has shown that PPP1R9B localizes specifically to synapses in neurons, so optimized protocols should reveal this characteristic pattern of distribution .

What are the critical considerations for Western blot analysis of PPP1R9B?

Western blot analysis of PPP1R9B requires attention to several critical factors:

• Sample preparation:

  • For brain tissue: Use appropriate lysis buffers containing protease inhibitors

  • Positive control samples: Mouse brain tissue, U-87MG cells, K-562 cells are documented to express PPP1R9B

• Gel electrophoresis conditions:

  • Use reducing conditions as specified in R&D Systems' protocol

  • Consider gradient gels (4-12%) to better resolve the high molecular weight of PPP1R9B (90-130 kDa)

• Antibody dilution and incubation:

  • Primary antibody: Most protocols recommend 1:500-1:2000 dilution for Western blot applications

  • For example, R&D Systems protocol used 1 μg/mL of their antibody (AF6465)

  • Secondary antibody: Use appropriate HRP-conjugated secondary antibody (e.g., Anti-Sheep IgG for sheep primary antibodies)

• Detection system:

  • Use enhanced chemiluminescence (ECL) or other sensitive detection methods

  • Exposure time may need optimization as PPP1R9B expression varies between tissues

• Molecular weight considerations:

  • Despite a calculated molecular weight of 89 kDa, PPP1R9B typically migrates at 90-130 kDa

  • This higher molecular weight should be used as the reference point when identifying PPP1R9B bands

For accurate Western blot analysis, researchers should be aware that PPP1R9B may show different banding patterns depending on the tissue source and experimental conditions.

How can I effectively use PPP1R9B antibodies for co-immunoprecipitation experiments to study protein-protein interactions?

PPP1R9B functions as a scaffold protein in multiple signaling pathways, making co-immunoprecipitation (co-IP) a valuable approach to study its interactions. For effective co-IP experiments:

• Antibody selection: Choose PPP1R9B antibodies specifically validated for immunoprecipitation. For example:

  • Proteintech antibody 55129-1-AP is validated for IP applications with recommended usage of 0.5-4.0 μg for 1.0-3.0 mg of total protein lysate

  • Assay Genie antibodies (CAB17229, CAB17230) have also been used successfully in pull-down experiments

• Lysis conditions: Use mild lysis buffers that preserve protein-protein interactions:

  • Non-denaturing buffers containing 1% NP-40 or Triton X-100

  • Include protease and phosphatase inhibitors to prevent degradation and preserve phosphorylation states

  • Consider crosslinking agents for transient interactions

• Experimental design:

  • Pre-clear lysates with appropriate control IgG and protein A/G beads

  • Incubate clarified lysates with PPP1R9B antibody overnight at 4°C

  • Include appropriate negative controls (non-specific IgG of the same species)

  • Consider positive controls (known PPP1R9B interaction partners like PP1)

• Analysis of interaction partners:

  • Western blot analysis using antibodies against suspected binding partners

  • Mass spectrometry for unbiased identification of novel interaction partners

Known PPP1R9B interaction partners that can be investigated include:

• Protein phosphatase 1 (PP1)

• Actin filaments

• AMPA and NMDA glutamate receptors

• G-protein coupled receptors (including dopamine D2 receptors)

• Alpha-adrenergic receptors (ADRA1B)

• RGS2 and other regulatory proteins

This approach has been successfully used to demonstrate PPP1R9B's role in complex formation for dopaminergic neurotransmission through D2 receptors, linking receptors to downstream signaling molecules and the actin cytoskeleton .

What is the significance of PPP1R9B subcellular localization, and how can I optimize immunofluorescence techniques to study it?

PPP1R9B's subcellular localization is crucial to its function. According to GeneCards and other sources, PPP1R9B localizes to multiple cellular compartments, including:

• Cell junctions

• Cell membrane

• Cell projections

• Cytoplasm

• Nucleus

• Adherens junctions

• Cytoskeleton

• Dendritic spines

• Filopodia

• Lamellipodia

• Ruffle membrane

• Synapses

To optimize immunofluorescence techniques for studying PPP1R9B localization:

• Fixation method:

  • For neuronal cultures: Immersion fixation with 4% paraformaldehyde (PFA) for 15-20 minutes

  • For tissue sections: Perfusion fixation with 4% PFA followed by post-fixation

• Permeabilization:

  • Use 0.1-0.3% Triton X-100 for adequate antibody penetration

  • Duration should be optimized (typically 5-15 minutes) to prevent antigen loss

• Blocking:

  • Use 5-10% serum from the species of the secondary antibody

  • Consider adding 1-3% BSA to reduce background

• Antibody selection and dilution:

  • Choose antibodies validated for immunofluorescence (IF) applications

  • Recommended dilutions for IF typically range from 1:50-1:200

  • R&D Systems protocol used 10 μg/mL of their antibody (AF6465) for 3 hours at room temperature

• Co-staining strategy:

  • Combine PPP1R9B antibody with markers for specific subcellular compartments:

    • Beta-III Tubulin for neuronal cytoskeleton (as used in R&D Systems protocol)

    • PSD-95 for postsynaptic densities

    • Synaptophysin for presynaptic terminals

    • Phalloidin for F-actin visualization

• Confocal microscopy settings:

  • Use appropriate laser power and gain settings to avoid saturation

  • Collect z-stacks for three-dimensional analysis of localization

  • Consider super-resolution microscopy for detailed subcellular localization studies

Research has shown that in neurons, PPP1R9B specifically localizes to synapses, consistent with its role in regulating synaptic transmission and plasticity . The R&D Systems protocol demonstrated clear synaptic localization in rat hippocampal neurons using their AF6465 antibody .

How do I address the discrepancy between the calculated molecular weight (89 kDa) and the observed molecular weight (120-140 kDa) of PPP1R9B in Western blot analysis?

The discrepancy between calculated and observed molecular weights of PPP1R9B is a common challenge in Western blot analysis that requires careful interpretation:

• Possible explanations for the discrepancy:

  • Post-translational modifications: PPP1R9B undergoes extensive phosphorylation which can significantly alter its migration pattern

  • Protein structure and amino acid composition: The high proline content in certain regions (e.g., "VFQPPPPPPPAPSGDA..." sequence in the 250-350 aa region) can cause anomalous migration

  • Alternative splicing: PPP1R9B has isoform variants that may affect migration patterns

• Verification strategies:

  • Use recombinant PPP1R9B protein as a positive control

  • Perform immunoprecipitation followed by Western blot to confirm specificity

  • Consider phosphatase treatment of samples to determine if phosphorylation contributes to the shift

  • Include tissue samples known to express high levels of PPP1R9B (e.g., brain tissue)

• Expected patterns in different samples:

  • Human/rat brain lysates: PPP1R9B detected at 90-120 kDa

  • Mouse brain tissue: PPP1R9B typically observed at 120-130 kDa

  • Cell lines: May show variation in molecular weight between 120-140 kDa

• Documentation in literature:

  • PPP1R9B (89 kDa predicted) running anomalously at 120-140 kDa is well-documented in multiple sources

  • R&D Systems specifically notes that PPP1R9B is detected at "approximately 90-120 kDa" despite its calculated lower molecular weight

This discrepancy is common enough that it should be considered a normal characteristic of PPP1R9B rather than an experimental artifact. Researchers should expect to see PPP1R9B bands at higher molecular weights than the calculated 89 kDa in Western blot analysis.

What are the potential pitfalls in interpreting PPP1R9B antibody reactivity across different brain regions and cell types?

Interpreting PPP1R9B antibody reactivity across different brain regions and cell types presents several potential pitfalls:

• Differential expression levels:

  • PPP1R9B is expressed at highest levels in hippocampus and at lower levels in cortex, cerebellum, and brainstem

  • This natural variation could be misinterpreted as antibody specificity issues if appropriate positive controls aren't included

• Cell type-specific post-translational modifications:

  • Different neuronal populations may exhibit cell type-specific post-translational modifications of PPP1R9B

  • These modifications can affect antibody binding efficiency and create apparent differences in expression

• Alternative splicing or isoform expression:

  • There is at least one isoform variant that shows an Ala insertion after both Ala158 and Ala165, coupled to a premature truncation after Arg576

  • Different regions or cell types may express different isoforms that may react differently with antibodies

• Background staining and cross-reactivity:

  • Non-specific binding can be particularly problematic in brain tissue due to high lipid content

  • PPP1R9B has multiple aliases and related family members (e.g., PPP1R9A) that may cross-react with some antibodies

• Methodological considerations:

  • Fixation artifacts: Different brain regions may fix differently, affecting epitope accessibility

  • Antigen retrieval efficiency: Varies across tissue types and can influence staining patterns

  • Antibody penetration: Differences in tissue density can affect antibody penetration

Best practices to mitigate these pitfalls:

• Include multiple positive controls (e.g., hippocampus for high expression)

• Use knockout or knockdown controls when available

• Compare results from multiple antibodies targeting different epitopes

• Validate findings with complementary techniques (e.g., in situ hybridization)

• Consider using multiple dilutions to establish optimal conditions for each brain region

Remember that PPP1R9B localizes to dendritic spines in neurons but also to aspiny neurons such as GABAergic interneurons , which may create complex distribution patterns in brain tissue sections.

How can PPP1R9B antibodies be effectively used to investigate the protein's role in neurological disorders?

PPP1R9B has been implicated in neurological disorders, making it an important target for translational research. Effective use of PPP1R9B antibodies in this context involves:

• Comparative expression analysis:

  • Compare PPP1R9B expression levels in brain tissue from patients with neurological disorders versus controls

  • Techniques: Western blot (WB) and immunohistochemistry (IHC) with validated antibodies (e.g., 55129-1-AP for both WB and IHC )

  • Quantify expression differences using appropriate normalization controls

• Subcellular localization changes:

  • Investigate alterations in PPP1R9B localization in disease states using immunofluorescence

  • Co-stain with markers for dendritic spines, synapses, and specific neuronal populations

  • R&D Systems' protocol for detecting PPP1R9B in rat hippocampal neurons provides a good starting point

• Protein-protein interaction alterations:

  • Use co-immunoprecipitation with PPP1R9B antibodies to identify changes in interaction partners in disease states

  • Compare interaction profiles between healthy and diseased tissues

  • Focus on known partners implicated in neurological disorders (e.g., glutamate receptors, PP1)

• Post-translational modification analysis:

  • Combine PPP1R9B immunoprecipitation with phospho-specific antibodies or mass spectrometry

  • Compare PTM profiles between control and disease samples

  • Correlate modifications with functional outcomes

• Animal models and intervention studies:

  • Use PPP1R9B antibodies to validate knockdown/knockout efficiency in animal models

  • Monitor expression changes in response to therapeutic interventions

  • Assess restoration of normal PPP1R9B localization/function as a treatment outcome measure

PPP1R9B's role in regulating PP1 activity, which influences synaptic transmission and plasticity, makes it particularly relevant to disorders like Alzheimer's disease and schizophrenia . Dysregulation of PP1 activity has been linked to these conditions, highlighting the importance of studying PPP1R9B's potential as a therapeutic target .

What methodological approaches can be used to investigate PPP1R9B's dual roles in both neuronal function and potential tumor suppression?

PPP1R9B has been implicated in both neuronal function and tumor suppression, requiring tailored methodological approaches to investigate these distinct roles:

• Comparative expression analysis across tissues:

  • Use Western blot and immunohistochemistry with PPP1R9B antibodies across neural tissues and tumor/normal pairs

  • Recommended antibodies: Proteintech 55129-1-AP for both WB (1:1000-1:8000) and IHC (1:20-1:200)

  • Compare expression levels using quantitative methods with appropriate loading controls

• Cell type-specific localization studies:

  • In neurons: Focus on dendritic spine and synaptic localization using immunofluorescence

  • In tumors: Examine nuclear versus cytoplasmic distribution to assess potential function

  • Use subcellular fractionation followed by Western blot to quantify distribution patterns

• Functional studies using cellular models:

  • Neuronal function: Use PPP1R9B antibodies in combination with electrophysiology to correlate expression/localization with synaptic function

  • Tumor suppression: Analyze cell proliferation, migration, and invasion in relation to PPP1R9B expression

  • The R&D Systems report highlights PPP1R9B's requirement for hepatocyte growth factor (HGF)-induced cell migration , connecting its cytoskeletal functions to potential roles in tumor biology

• Protein-protein interaction network analysis:

  • Use immunoprecipitation with PPP1R9B antibodies followed by mass spectrometry

  • Compare interactome in neuronal cells versus tumor cell lines

  • Focus on PP1-related interactions in neurons and potential tumor suppressor pathway interactions in other cell types

• Pathway-specific analyses:

  • Neuronal function: Examine glutamatergic signaling and cytoskeletal regulation

  • Tumor suppression: Investigate cell cycle regulation and migration pathways

  • Use phospho-specific antibodies to assess downstream signaling effects