PPP1R15B Antibody

What is PPP1R15B and what is its biological function?

PPP1R15B (Protein Phosphatase 1 Regulatory Subunit 15B), also known as CReP (Constitutive Repressor of eIF2α Phosphorylation), is a 713 amino acid protein belonging to the PPP1R15 family. The protein functions as a regulatory subunit that maintains low levels of eIF2α phosphorylation in unstressed cells by promoting its dephosphorylation through protein phosphatase 1 (PP1) . PPP1R15B forms a complex with PP1 and NCK1/2 to facilitate this dephosphorylation process, which is essential for controlling protein synthesis, especially during stress conditions . The expression of PPP1R15B occurs in various tissues with particularly high levels detected in brain, liver, and kidney tissues . Recent studies have indicated that PPP1R15B plays a critical role in the endoplasmic reticulum (ER) stress response and translation regulation .

What are the common applications for PPP1R15B antibodies in research?

PPP1R15B antibodies have been validated for multiple research applications, with varying specificity and sensitivity across different experimental platforms:

When designing experiments, researchers should consider the specific application requirements and select antibodies validated for their intended use .

How should I select the appropriate PPP1R15B antibody for my specific experimental needs?

Selecting the appropriate PPP1R15B antibody requires consideration of several key factors:

• Experimental Application: First determine which application (WB, IF, IHC, IP, etc.) is needed, then select an antibody specifically validated for that application. For example, antibody catalog #14634-1-AP has been validated for WB, IHC, IF/ICC, IP, and CoIP applications .

• Species Reactivity: Match the antibody's reactivity to your experimental model. Available PPP1R15B antibodies show reactivity with human samples, while some also react with mouse and rat samples . BLAST analysis can help predict cross-reactivity with other species – for example, some antibodies show high sequence identity with chimpanzee, gibbon, and marmoset (100%), as well as gorilla and monkey (92%) .

• Epitope Recognition: Consider which region of PPP1R15B the antibody recognizes. Some antibodies target specific amino acid regions (e.g., aa480-529, aa250-400) , which may be important depending on your research question, particularly if studying specific domains like the PP1 binding region.

• Clonality: Polyclonal antibodies offer broader epitope recognition but may have batch-to-batch variation, while recombinant antibodies provide higher consistency. Both types are available for PPP1R15B detection .

• Validation Data: Review the validation data provided by manufacturers, including Western blot images showing the expected molecular weight (typically 100-110 kDa for PPP1R15B) .

What are the differences between observed and calculated molecular weights for PPP1R15B?

This question addresses a common source of confusion for researchers working with PPP1R15B:

• Post-translational modifications: PPP1R15B may undergo modifications such as phosphorylation, glycosylation, or SUMOylation that increase its apparent molecular weight.

• Protein structure: The tertiary structure of the protein may cause it to migrate more slowly in SDS-PAGE than predicted based solely on amino acid composition.

• Isoform expression: Different isoforms of PPP1R15B may be expressed in different tissues or under different conditions.

When validating a new PPP1R15B antibody, researchers should expect to observe bands at 100-110 kDa rather than at the calculated 79 kDa. Multiple validation studies across different cell lines including HEK-293, MCF-7, A2780, SGC-7901, MDA-MB-231, and SKOV-3 cells have consistently shown this higher molecular weight band pattern .

What are the optimal storage and handling conditions for PPP1R15B antibodies?

Proper storage and handling of PPP1R15B antibodies is critical for maintaining their activity and specificity:

What are the recommended dilutions for PPP1R15B antibodies in different applications?

Proper antibody dilution is critical for obtaining specific signals while minimizing background. The following table summarizes recommended dilutions for different applications based on validated antibody performance:

When working with a new sample type or antibody lot, it is recommended to perform a dilution series to determine the optimal concentration for your specific experimental conditions. The optimal dilution provides the strongest specific signal with minimal background .

How can I validate the specificity of a PPP1R15B antibody?

Validating antibody specificity is crucial for ensuring reliable experimental results. For PPP1R15B antibodies, consider these validation approaches:

• Positive Controls: Use cell lines known to express PPP1R15B, such as HEK-293, MCF-7, SGC-7901, MDA-MB-231, and SKOV-3 cells, which have been validated to show positive Western blot detection .

• Knockdown/Knockout Verification: Utilize PPP1R15B knockdown or knockout samples as negative controls. Several published studies have employed knockdown/knockout approaches to validate PPP1R15B antibodies .

• Peptide Competition Assay: Pre-incubate the antibody with the immunizing peptide before application to your sample. Specific binding should be blocked by the peptide, resulting in loss of signal.

• Multiple Antibody Comparison: Use multiple antibodies targeting different epitopes of PPP1R15B. Consistent results across different antibodies increase confidence in specificity.

• Expected Molecular Weight: Confirm that the detected band appears at the expected molecular weight (100-110 kDa for PPP1R15B) , although be aware of the discrepancy from the calculated weight (79 kDa) as discussed earlier.

• Cross-Reactivity Testing: If working across species, verify specificity in each species of interest, as cross-reactivity can vary. For example, while some antibodies show 100% sequence identity with human PPP1R15B, they may show lower identity with other species (e.g., 91% for bovine, 84% for bat) .

• Immunoprecipitation-Mass Spectrometry: For rigorous validation, immunoprecipitate PPP1R15B and confirm its identity by mass spectrometry.

How can PPP1R15B antibodies be used to study protein-protein interactions?

PPP1R15B functions through interactions with other proteins, particularly PP1 and NCK1/2. Antibodies can be powerful tools for studying these interactions:

• Co-Immunoprecipitation (Co-IP): PPP1R15B antibodies can be used to pull down PPP1R15B and its binding partners from cell lysates. For example, the interaction between PPP1R15B and PP1 can be studied by immunoprecipitating PPP1R15B and then probing for PP1 in Western blots . This technique is particularly useful for studying how mutations in PPP1R15B (such as R658C) affect protein-protein interactions.

• Immunofluorescence Co-localization: Using PPP1R15B antibodies in combination with antibodies against potential interacting proteins can reveal co-localization in cellular compartments. PPP1R15B antibodies have been validated for immunofluorescence in various cell lines including HepG2 and SH-SY5Y cells .

• Proximity Ligation Assay (PLA): This technique can detect protein-protein interactions in situ with high sensitivity and specificity using PPP1R15B antibodies in combination with antibodies against potential interaction partners.

• Pull-down Assays with Recombinant Proteins: Combining immunoprecipitation of endogenous PPP1R15B with in vitro binding assays using recombinant proteins can help map interaction domains and assess binding affinity.

• Antibody-based Disruption of Interactions: In some experimental settings, antibodies targeting specific domains of PPP1R15B can be used to disrupt protein-protein interactions, helping to elucidate their functional significance.

For studying the critical interaction between PPP1R15B and PP1, researchers have successfully employed GFP-tagged PPP1R15B (wild-type or mutant) co-expressed with PP1A, followed by immunoprecipitation using anti-GFP antibodies to assess the impact of mutations on binding efficiency .

What role does PPP1R15B play in disease mechanisms, and how can antibodies help study this?

PPP1R15B has been implicated in several disease mechanisms, particularly those involving cellular stress responses and protein synthesis regulation:

• Diabetes and Metabolic Disorders: A missense mutation (R658C) in PPP1R15B has been identified in two siblings with a syndrome including young-onset diabetes, microcephaly, and short stature . This mutation affects a conserved amino acid within the PP1 binding domain, decreasing PP1 binding and eIF2α dephosphorylation, ultimately resulting in β-cell apoptosis. PPP1R15B antibodies can be used to:

  • Detect expression levels in patient samples

  • Study the cellular localization of mutant PPP1R15B

  • Assess the impact of therapeutic interventions on PPP1R15B function

• Neurodegenerative Diseases: PPP1R15B is highly expressed in brain tissues and is involved in the integrated stress response, which is implicated in various neurodegenerative conditions. Antibodies can help:

  • Analyze PPP1R15B expression patterns in different brain regions using IHC (validated for mouse brain and cerebellum tissues)

  • Investigate PPP1R15B's role in neuronal stress responses through IF/ICC in neuronal cell lines like SH-SY5Y

• Cancer Research: Gene overexpression can occur at chromosome 1q32.1, which includes PPP1R15B, suggesting involvement in the pathogenesis of glioblastoma multiforme (GBM) . PPP1R15B antibodies enable:

  • Expression profiling in tumor versus normal tissue

  • Analysis of PPP1R15B's role in cancer cell survival under stress conditions

  • Investigation of PPP1R15B as a potential biomarker or therapeutic target

• Cellular Stress Response Studies: PPP1R15B is associated with oxidative stress protection, with knockdown of PPP1R15B showing strong protection against oxidative and peroxynitrite stress . Antibodies facilitate:

  • Monitoring PPP1R15B expression changes during stress conditions

  • Studying post-translational modifications in response to cellular stress

  • Investigating the dynamics of PPP1R15B-containing complexes during stress response

How can PPP1R15B antibodies be used to study eIF2α phosphorylation and translation regulation?

PPP1R15B plays a crucial role in regulating eIF2α phosphorylation, which is central to protein synthesis control. Antibodies can be instrumental in studying this regulatory pathway:

• Dephosphorylation Assays: PPP1R15B antibodies can be used to immunoprecipitate the PPP1R15B-PP1 complex for in vitro dephosphorylation assays. This approach was used to demonstrate that the R658C mutation in PPP1R15B decreases eIF2α dephosphorylation activity .

• Phosphorylation State Monitoring: Using PPP1R15B antibodies in combination with phospho-specific eIF2α antibodies in Western blots or immunofluorescence allows researchers to correlate PPP1R15B expression levels with eIF2α phosphorylation states.

• Stress Response Studies: PPP1R15B antibodies can track changes in PPP1R15B expression and localization during various stress conditions (ER stress, oxidative stress), helping to understand how these stresses affect translation regulation.

• Genetic Manipulation Verification: When performing knockdown, knockout, or overexpression of PPP1R15B to study its effects on translation, antibodies are essential for confirming the success of these genetic manipulations.

• Drug Studies: PPP1R15B-PP1 complex can be inhibited by drugs like Salubrinal that protect cells from endoplasmic reticulum stress . Antibodies help assess how such drugs affect PPP1R15B expression, localization, and complex formation.

• Structure-Function Analysis: By comparing wild-type and mutant PPP1R15B (like the R658C mutant) using immunoprecipitation and subsequent functional assays, researchers can map critical domains for eIF2α regulation .

For example, HEK293T cells transfected with EGFP-tagged wild-type or mutant PPP1R15B, together with mouse PP1A expression plasmid, can be lysed and immunoprecipitated using anti-GFP antibody. The immunoprecipitates can then be used for dephosphorylation studies to assess the impact of mutations on regulatory function .