Acetyl-HSP90AA1 (K435) Antibody

What is Acetyl-HSP90AA1 (K435) antibody and what specific epitope does it recognize?

Acetyl-HSP90AA1 (K435) antibody is a polyclonal antibody raised in rabbits that specifically recognizes the heat shock protein 90 alpha (HSP90AA1) only when acetylated at lysine residue 435 (K435). The antibody is designed to detect endogenous levels of HSP90 protein exclusively when this specific post-translational modification is present . It was generated using a synthesized acetyl-peptide derived from human HSP90 surrounding the acetylation site of K435 . This high specificity makes it valuable for studying acetylation-dependent functions and regulations of HSP90AA1.

The antibody has been validated for detection of this modification in human, mouse, and rat samples, making it applicable across multiple model systems . It's important to note that this antibody is strictly for research use only (RUO) and should not be employed in diagnostic or therapeutic applications . The specificity for the acetylated form allows researchers to distinguish between modified and unmodified HSP90AA1, enabling studies on the functional consequences of this specific post-translational modification.

What are the recommended storage conditions and handling practices for maintaining antibody activity?

For optimal preservation of Acetyl-HSP90AA1 (K435) antibody activity, proper storage and handling are critical. The antibody should be stored at -20°C for up to one year from the date of receipt . Some suppliers may also recommend storage at -80°C as an alternative . The formulation consists of liquid in PBS containing 50% glycerol, 0.5% BSA, and 0.02% sodium azide, which helps maintain stability during storage .

Repeated freeze-thaw cycles should be strictly avoided as they can lead to protein denaturation and loss of antibody activity . When working with the antibody, it's advisable to aliquot it into smaller volumes upon first thawing to minimize the number of freeze-thaw cycles. Working dilutions should be prepared fresh before use and stored at 4°C for short periods only. The antibody concentration is standardized at 1 mg/mL, which allows for consistent dilution preparation . Additionally, all handling should be done using nuclease-free tubes and pipette tips to prevent contamination.

How should Acetyl-HSP90AA1 (K435) antibody be optimized for Western blot applications?

For sample preparation, effective protein extraction requires preserving acetylation modifications, so lysates should contain deacetylase inhibitors (e.g., trichostatin A, nicotinamide) to prevent loss of the acetylation signal during sample processing. Cell lysis buffers should be supplemented with protease inhibitor cocktails to prevent degradation of the target protein. After SDS-PAGE separation, proteins should be transferred to a PVDF or nitrocellulose membrane, with PVDF often providing better results for detecting post-translational modifications.

Since HSP90AA1 has a molecular weight of approximately 85kDa on SDS-PAGE , appropriate molecular weight markers should be included. Blocking should be performed with 5% non-fat dry milk or BSA in TBST, with BSA often preferred for phospho-specific and acetyl-specific antibodies. Primary antibody incubation should occur overnight at 4°C to enhance specific binding. After thorough washing, an appropriate HRP-conjugated secondary anti-rabbit antibody should be applied, followed by development using enhanced chemiluminescence reagents.

What are the recommended protocols for applying Acetyl-HSP90AA1 (K435) antibody in ELISA assays?

For ELISA applications, the Acetyl-HSP90AA1 (K435) antibody requires significant dilution, with manufacturers recommending a dilution ratio of 1:20000 . This high dilution factor reflects the antibody's sensitivity in ELISA format and helps minimize background signal while conserving antibody.

When designing an ELISA protocol, researchers should coat microplate wells with a capture antibody against HSP90AA1 (not acetylation-specific) to first immobilize the target protein. After blocking with an appropriate buffer containing BSA (typically 1-3%), sample lysates containing HSP90AA1 should be added. The Acetyl-HSP90AA1 (K435) antibody would then be applied as the detection antibody, followed by an HRP-conjugated secondary antibody and appropriate substrate for colorimetric or chemiluminescent detection.

For quantitative analysis, researchers should include a standard curve using recombinant acetylated HSP90AA1 protein or synthetic acetylated peptides. Controls should include samples treated with deacetylase inhibitors (positive control) and deacetylase enzymes (negative control) to validate specificity. Additionally, competing with excess non-acetylated and acetylated peptides can help confirm antibody specificity. Signal development time should be optimized through preliminary experiments, as extended incubation may increase background signal.

How can Acetyl-HSP90AA1 (K435) antibody be validated to ensure acetylation site specificity?

Validating the specificity of Acetyl-HSP90AA1 (K435) antibody is crucial for ensuring experimental reliability. A comprehensive validation approach should include multiple methodologies. First, researchers should perform peptide competition assays using both acetylated and non-acetylated K435 peptides. If the antibody is specific, only the acetylated peptide should block antibody binding in Western blot or ELISA.

Second, site-directed mutagenesis of K435 to arginine (K435R, which cannot be acetylated) should abolish antibody recognition. Comparing wild-type HSP90AA1 with K435R mutant expression can definitively confirm antibody specificity. Third, treatment of cells with histone deacetylase inhibitors (HDACi) like trichostatin A should increase K435 acetylation and antibody signal, while deacetylase overexpression should decrease signal.

Fourth, performing immunoprecipitation with the acetyl-specific antibody followed by mass spectrometry analysis can confirm the precise acetylation site being recognized. Fifth, testing the antibody on samples from HSP90AA1 knockout cells or tissues provides an essential negative control. Finally, comparing results with alternative antibodies targeting the same modification from different vendors or production batches helps establish reproducibility and reliability of findings.

What role does acetylation at K435 play in regulating HSP90AA1 chaperone function?

Acetylation at K435 of HSP90AA1 represents a critical post-translational modification that significantly impacts its chaperone function. HSP90AA1 functions as a molecular chaperone that promotes maturation, structural maintenance, and proper regulation of specific target proteins involved in cell cycle control and signal transduction . The chaperone activity of HSP90AA1 is intrinsically linked to its ATPase activity, which drives conformational changes in client proteins necessary for their activation.

Acetylation at K435 appears to modulate HSP90AA1's interaction with co-chaperones and client proteins. These co-chaperones act as adapters that simultaneously interact with specific clients and HSP90 itself, forming functional chaperone complexes. The addition of an acetyl group at K435 alters the chemical properties of this region, potentially affecting protein-protein interactions and ATP binding/hydrolysis cycles.

Research methodologies to investigate these functional consequences include combining the Acetyl-HSP90AA1 (K435) antibody with immunoprecipitation to identify differential binding partners when K435 is acetylated versus unacetylated. Additionally, site-directed mutagenesis studies comparing wild-type HSP90AA1 with K435Q (acetylation-mimicking) and K435R (acetylation-preventing) mutants can elucidate the functional impact of this modification on chaperone activity, client protein maturation, and cellular responses to stress conditions.

How can Acetyl-HSP90AA1 (K435) antibody be utilized in cancer research, particularly breast cancer studies?

The Acetyl-HSP90AA1 (K435) antibody offers significant value for cancer research, especially in breast cancer studies. Recent evidence indicates that pretreatment plasma HSP90AA1, in combination with other markers, can predict breast cancer onset and metastasis risk . This finding positions HSP90AA1 as a potentially valuable biomarker for early detection and prognosis assessment in breast cancer patients.

For researchers investigating this connection, several methodological approaches are recommended. First, immunohistochemistry analysis of breast tumor tissues and adjacent normal tissues using the Acetyl-HSP90AA1 (K435) antibody can reveal differences in acetylation patterns. Second, comparing acetylation levels across breast cancer subtypes (luminal A, luminal B, HER2-enriched, and triple-negative) may uncover subtype-specific alterations. Third, correlation analyses between K435 acetylation and clinical parameters (tumor size, lymph node status, metastasis) can identify potential prognostic value.

Additionally, researchers can examine relationships between acetylated HSP90AA1 and client proteins relevant to breast cancer, such as estrogen receptor, HER2, and various kinases. Mechanistic studies could involve manipulating acetylation at K435 through HDAC inhibitors or site-directed mutagenesis and observing effects on cancer cell proliferation, migration, and response to therapy. Since early detection significantly improves survival rates (5-year survival of 90% for early-stage versus 27% for metastatic breast cancer) , investigating plasma acetylated HSP90AA1 as a non-invasive biomarker represents a promising research direction.

What methodological approaches should be considered when studying HSP90AA1 acetylation in clinical samples?

When studying HSP90AA1 acetylation in clinical samples, researchers face unique challenges that require specialized methodological approaches. For blood plasma or serum samples, an optimized protocol would begin with careful sample collection and processing to prevent protein degradation. Protease and deacetylase inhibitors should be added immediately upon collection. For tissue samples, flash freezing or appropriate fixation is critical to preserve post-translational modifications.

Protein extraction from clinical samples requires careful buffer optimization. A recommended approach is to use buffers containing sodium butyrate (5-10 mM) or other HDAC inhibitors to maintain acetylation status. For immunoprecipitation, pre-clearing samples with protein A/G beads helps reduce non-specific binding in complex clinical specimens. When applying the Acetyl-HSP90AA1 (K435) antibody for Western blotting of clinical samples, longer blocking times (2+ hours) and overnight primary antibody incubation at 4°C can improve specificity.

For larger clinical cohorts, developing an ELISA-based detection method using the Acetyl-HSP90AA1 (K435) antibody (1:20000 dilution) could enable higher throughput screening. This would require careful validation against Western blot results from a subset of samples. Additionally, researchers should consider including age-matched and sex-matched controls, as HSP90AA1 expression and acetylation patterns may vary with demographic factors. Multiplexed analysis combining Acetyl-HSP90AA1 (K435) detection with other cancer biomarkers could enhance the diagnostic and prognostic value, as suggested by findings that HSP90AA1 combined with other markers improves prediction of breast cancer risk .

What are common technical challenges when working with Acetyl-HSP90AA1 (K435) antibody and how can they be addressed?

Working with Acetyl-HSP90AA1 (K435) antibody presents several technical challenges that researchers should anticipate and address methodically. One common issue is weak or absent signal in Western blot applications, which may result from insufficient acetylation levels in samples. This can be addressed by treating cells with HDAC inhibitors before lysis to enhance acetylation. Additionally, using a more sensitive detection system such as enhanced chemiluminescence plus (ECL+) or fluorescently labeled secondary antibodies may improve signal detection.

Another challenge is non-specific binding, manifesting as multiple bands on Western blots. This can be mitigated by optimizing blocking conditions (trying different blocking agents like 5% BSA instead of milk), increasing antibody dilution from 1:500 toward 1:2000 , extending washing steps, and potentially including a low concentration of SDS (0.05-0.1%) in wash buffers to reduce non-specific interactions. Additionally, confirming the molecular weight of detected bands against the expected 85kDa for HSP90AA1 is essential.

Inconsistent results between experiments can be addressed by standardizing lysate preparation, ensuring consistent protein loading, and including positive controls (HDAC inhibitor-treated samples) and negative controls (samples expressing K435R mutant) in each experiment. For ELISA applications where background signal is problematic, optimizing antibody dilution toward the higher end of the recommended range (1:20000) and using specialized low-background ELISA buffers can improve signal-to-noise ratio.

How can researchers integrate Acetyl-HSP90AA1 (K435) antibody into multi-parameter analyses of HSP90 post-translational modifications?

HSP90AA1 undergoes multiple post-translational modifications beyond acetylation, including phosphorylation, methylation, and ubiquitination, creating a complex "modification code" that collectively regulates its function. Researchers seeking to perform multi-parameter analyses of HSP90 modifications can implement several sophisticated approaches integrating the Acetyl-HSP90AA1 (K435) antibody.

Sequential immunoprecipitation represents one powerful approach: first immunoprecipitating with Acetyl-HSP90AA1 (K435) antibody, then performing a second immunoprecipitation on the eluted material using antibodies against other modifications (or vice versa). This reveals proteins carrying both modifications simultaneously. Alternatively, researchers can perform parallel immunoprecipitations from the same lysate with different modification-specific antibodies, followed by comparative proteomic analysis to identify unique and overlapping client proteins or co-chaperones.

For microscopy-based approaches, multi-color immunofluorescence combining Acetyl-HSP90AA1 (K435) antibody with antibodies against other HSP90 modifications can reveal subcellular co-localization patterns. Mass spectrometry approaches offer perhaps the most comprehensive analysis: immunoprecipitation with Acetyl-HSP90AA1 (K435) antibody followed by tryptic digestion and LC-MS/MS analysis can identify not only K435 acetylation but also co-occurring modifications on the same protein molecule. Finally, creating a stable cell line expressing tagged HSP90AA1 can facilitate chromatin immunoprecipitation (ChIP) experiments to investigate whether acetylation at K435 affects HSP90's association with specific genomic regions when it functions in transcriptional regulation complexes.