fam219a Antibody

What is FAM219A and why is it significant in research?

FAM219A (Family with sequence similarity 219 member A), previously annotated as C9orf25 (Chromosome 9 open reading frame 25), is a protein-coding gene located on chromosome 9 in humans . While its specific function remains under investigation, researchers utilize FAM219A antibodies for detection and localization studies in human tissues and cells. The protein is primarily studied in contexts of cellular localization, expression patterns across tissues, and potential roles in cellular functions . The importance of FAM219A in research stems from efforts to understand the functions of previously uncharacterized genes and their encoded proteins.

FAM219A is characterized by the following molecular properties:

The amino acid sequence above represents the immunogen used in antibody production and corresponds to a portion of the full FAM219A protein .

How should FAM219A antibodies be stored for optimal performance?

Proper storage is crucial for maintaining antibody functionality. For FAM219A antibodies, the following storage conditions are recommended:

• Store at -20°C for long-term preservation

• For short-term storage (less than a month), refrigeration at 4°C is acceptable

• Avoid repeated freeze-thaw cycles to prevent antibody degradation

• Antibodies are typically supplied in a stabilizing buffer containing glycerol (40-50%) and PBS (pH 7.2-7.4)

• Some formulations may contain sodium azide (0.02%) as a preservative

Aliquoting the antibody upon receipt is recommended for antibodies without glycerol, though for formulations with glycerol (as is common with FAM219A antibodies), aliquoting may not be necessary for -20°C storage .

How do polyclonal and monoclonal FAM219A antibodies differ in research applications?

The available FAM219A antibodies are predominantly polyclonal in nature, produced in rabbits against specific epitopes of the human FAM219A protein . This has significant implications for research:

Research requiring absolute specificity for a single epitope might benefit from monoclonal antibodies, though these appear to be less common for FAM219A based on the available information .

What validation strategies should be employed to confirm FAM219A antibody specificity?

Rigorous validation is essential for antibody-based research. For FAM219A antibodies, comprehensive validation should include:

• Blocking/competition assays: Using recombinant FAM219A protein antigen to confirm specificity. Commercially available blocking agents include the recombinant protein with N-terminal His6-ABP tag corresponding to human FAM219A, expressed in E. coli .

• Positive and negative controls:

  • Positive: Tissues/cells known to express FAM219A

  • Negative: Tissues/cells with confirmed absence of FAM219A or samples with FAM219A knockdown/knockout

• Multiple antibody validation: Using different antibodies targeting distinct epitopes of FAM219A to confirm consistent patterns.

• Orthogonal techniques: Complementing antibody-based detection with RNA-based methods (RT-PCR, RNA-seq) to correlate protein detection with mRNA expression.

• Western blot analysis: Confirming specific detection of a protein of the expected molecular weight (approximately 25 kDa for FAM219A) .

Recent enhanced validation approaches also incorporate siRNA knockdown and/or CRISPR/Cas9 gene editing to generate truly negative controls, though specific data for such validation of FAM219A antibodies was not present in the search results .

What factors influence the optimization of immunohistochemistry protocols for FAM219A detection?

Optimizing immunohistochemistry (IHC) protocols for FAM219A detection requires consideration of several factors:

A systematic approach to optimization involves testing multiple conditions in parallel using known positive control tissues. Documentation of all parameters is essential for reproducibility across experiments .

How should cross-reactivity testing be performed for FAM219A antibodies?

Cross-reactivity testing is essential to ensure the specificity of FAM219A antibody staining, especially given the polyclonal nature of available antibodies. A comprehensive approach includes:

• Computational analysis: Compare FAM219A sequence with potential cross-reactive proteins to identify similar epitopes.

• Blocking experiments:

  • Pre-incubate the antibody with excess recombinant FAM219A protein (0.5mg/mL concentration)

  • Apply the blocked antibody in parallel with unblocked antibody

  • Specific staining should be eliminated or significantly reduced in the blocked condition

• Panel testing: Evaluate reactivity across a panel of tissues with different expression levels of FAM219A and related proteins.

• Negative controls:

  • Primary antibody omission

  • Non-specific IgG from the same species (rabbit for most FAM219A antibodies)

  • Tissues known to lack FAM219A expression

The recombinant FAM219A protein antigen available for blocking experiments contains the sequence MEEIDRFQVPTAHSEMQPLDPAAASISDGDCDAREGESVAMNYKPSPLQVKLEKQRELARKGSLKNGSM, which corresponds to the immunogen used in antibody production .

What are the optimal fixation and sample preparation methods for FAM219A immunodetection?

Proper sample preparation significantly impacts the success of FAM219A detection. Recommended protocols include:

For paraffin-embedded tissues, subsequent processing steps include:

• Dehydration through ascending ethanol series

• Clearing in xylene

• Infiltration with paraffin

• Sectioning at 4-6 μm thickness

• Mounting on positively charged slides

Antigen retrieval is particularly important for FAM219A detection in formalin-fixed tissues, with heat-induced retrieval in citrate buffer (pH 6.0) commonly employed to expose epitopes masked during fixation .

How can multiplexed detection of FAM219A with other markers be achieved?

Multiplexed detection allows researchers to examine the relationship between FAM219A and other proteins of interest within the same sample:

• Sequential immunofluorescence:

  • Use primary antibodies from different species (e.g., rabbit anti-FAM219A with mouse anti-protein X)

  • Detect with species-specific secondary antibodies conjugated to different fluorophores

  • Include spectral controls to ensure no bleed-through between channels

• Multiplexed immunohistochemistry:

  • Sequential rounds of staining with complete stripping between rounds

  • Different chromogens for each marker (e.g., DAB for FAM219A, AP-Red for protein X)

• Tyramide signal amplification (TSA):

  • Allows use of multiple primary antibodies from the same species

  • Each round includes HRP-mediated deposition of different fluorophore-conjugated tyramides

  • Heat-mediated antibody stripping between rounds

For optimal results with FAM219A, the unconjugated primary antibodies can be used at 1:200-1:500 dilution for IHC and 0.25-2 μg/mL for immunofluorescence .

How can background staining issues with FAM219A antibodies be mitigated?

Background staining is a common challenge in immunodetection. Specific strategies for FAM219A antibodies include:

When using the affinity-isolated FAM219A antibodies, dilution optimization is critical—starting with the recommended 1:200-1:500 range for IHC and adjusting based on signal-to-noise ratio .

What controls are essential for interpreting FAM219A localization studies?

Robust controls are crucial for accurate interpretation of FAM219A localization:

• Technical controls:

  • Primary antibody omission

  • Isotype control (rabbit IgG)

  • Absorption control using recombinant FAM219A protein (0.5mg/mL)

• Biological controls:

  • Known positive tissues/cells

  • Known negative tissues/cells

  • siRNA knockdown of FAM219A

• Co-localization controls:

  • Established markers for subcellular compartments

  • Multiple antibodies against different regions of FAM219A

  • Correlation with tagged overexpression studies

• Signal validation:

  • Comparison of detection methods (IF vs. IHC)

  • Orthogonal validation with RNA expression data

  • Western blot confirmation of specificity

For quantitative analyses, include standardization controls to account for batch effects and establish threshold values for positive staining .

How should researchers interpret discrepancies in FAM219A detection across different techniques?

Discrepancies between detection methods may arise from technical and biological factors:

When discrepancies occur:

• Evaluate epitope accessibility: Different fixation methods may differentially preserve epitopes.

• Consider protein state: Native conformation vs. denatured state affects antibody recognition.

• Assess expression level thresholds: Each method has different detection thresholds.

• Examine post-translational modifications: These may affect antibody binding in tissue-specific or context-dependent ways.

• Validate with orthogonal approaches: Combine antibody-based detection with mRNA analysis, mass spectrometry, or genetic manipulation.

For FAM219A specifically, comparing results obtained with the unconjugated polyclonal antibodies across different applications (using recommended concentrations: 1:200-1:500 for IHC, 0.25-2 μg/mL for IF) can help resolve discrepancies .