ART5 Antibody

What is ART5 and what cellular functions does it perform?

ART5 (Ecto-ADP-ribosyltransferase 5) belongs to a class of enzymes that catalyze the transfer of an ADP-ribose group from NAD to arginine residues on target proteins like G proteins . It is a secreted protein involved in post-translational modifications that can alter protein function and cellular signaling . ART5 has been implicated in immune regulation and has been associated with modulating immune responses in different cell types, making it a significant target for studies in molecular biology and immunology . Its role in cellular signaling pathways contributes to our understanding of immune function, inflammation, and autoimmune disorders .

What are the molecular characteristics of the ART5 protein?

ART5 has a calculated molecular weight of 32 kDa (292 amino acids), but is typically observed at 35-40 kDa in Western blot analyses, suggesting post-translational modifications . The protein belongs to the Arg-specific ADP-ribosyltransferase family and has several alternative names including ADP-ribosyltransferase C2 and C3 toxin-like 5, ARTC5, and Mono(ADP-ribosyl)transferase 5 . The protein sequence for immunogen development often targets amino acids 23-200 of human ART5 (NP_443750.2), which contains the functional domain of the protein . In mouse tissues, the antibody typically detects a 43 kDa ART5 protein, particularly in liver and testis samples .

What are the common applications for ART5 antibodies in research?

ART5 antibodies are versatile research tools applicable across multiple experimental platforms. The primary applications include:

For optimal results, researchers should perform antigen retrieval with TE buffer pH 9.0 when conducting IHC; alternatively, citrate buffer pH 6.0 may be used . It's highly recommended that researchers titrate these antibodies in each testing system to obtain optimal results, as performance can be sample-dependent .

How can I optimize ART5 antibody performance for difficult tissue samples?

When working with challenging tissue samples, optimization of antigen retrieval methods is critical for ART5 detection. For formalin-fixed paraffin-embedded (FFPE) tissues, the standard TE buffer at pH 9.0 is recommended, but some tissues may require alternative approaches . For tissues with high background or weak signal, extending the antigen retrieval time or adjusting the buffer concentration can improve results.

For mouse testis tissue, which often presents detection challenges, Western blotting should be performed with dilutions between 1:300-1:500 to achieve optimal signal-to-noise ratio . Additionally, blocking with 5% non-fat milk or BSA for extended periods (2+ hours) can reduce non-specific binding that often plagues testicular tissue analysis . For particularly difficult samples, consider using signal enhancement systems specifically designed for IHC applications while maintaining antibody specificity.

What are the known cross-reactivity patterns of ART5 antibodies across species?

ART5 antibodies demonstrate specific cross-reactivity patterns that researchers should consider when designing experiments:

When studying ART5 in non-human primates or other mammals, preliminary validation is strongly recommended as sequence homology varies . For researchers working across multiple species, selecting antibodies raised against highly conserved epitopes will maximize experimental consistency and data reliability .

How does ART5 expression differ across tissue types, and what implications does this have for experimental design?

ART5 expression exhibits significant tissue specificity that must be accounted for in experimental design. Based on antibody validation data, ART5 is prominently expressed in:

• Mouse testis tissue (strongly detected in Western blots)

• Mouse liver tissue (moderate expression)

• Human heart tissue (detectable with IHC)

• Human lung cancer tissue (variable expression patterns)

This differential expression pattern suggests tissue-specific regulatory mechanisms for ART5 function . When designing experiments, researchers should include appropriate positive control tissues to ensure antibody functionality, particularly when working with tissues not listed above . For comparative expression studies, normalization to housekeeping proteins specific to each tissue type is essential, as standard housekeeping proteins may vary across different tissues . Additionally, researchers should consider developmental stage and disease state, as ART5 expression may be altered in pathological conditions compared to healthy tissues .

What are the optimal protein extraction methods for ART5 detection in Western blotting?

For optimal ART5 detection in Western blotting, protein extraction methodology significantly impacts results. RIPA buffer supplemented with protease inhibitors is recommended for standard protein extraction . For membrane-associated fractions of ART5, consider using:

• Sequential extraction with PBS, high-salt buffer, and finally detergent to separate different cellular compartments

• Inclusion of phosphatase inhibitors if studying potential regulation through phosphorylation

• Gentle homogenization techniques to preserve protein integrity, especially for tissues like testis

The observed molecular weight of ART5 (35-40 kDa vs. calculated 32 kDa) suggests post-translational modifications that must be preserved during extraction . When loading samples, 20-50 μg of total protein typically yields optimal results for mouse testis tissue . For enhanced detection sensitivity, consider overnight primary antibody incubation at 4°C with dilutions between 1:500-1:1000 .

What controls should be implemented when validating ART5 antibody specificity?

Rigorous validation of ART5 antibody specificity requires implementing multiple controls:

Additional validation steps should include comparison of multiple antibodies targeting different epitopes of ART5 . For researchers using ART5 antibodies in novel applications or tissues, performing a titration series from 1:20 to 1:2000 is recommended to determine optimal concentration for specific experimental conditions .

How should researchers optimize fixation protocols for ART5 immunohistochemistry?

Optimizing fixation protocols is critical for successful ART5 immunohistochemistry. Based on validated protocols:

For formalin-fixed paraffin-embedded (FFPE) tissues:

• Fixation in 10% neutral buffered formalin for 24-48 hours (shorter for smaller specimens)

• Recommended antigen retrieval with TE buffer pH 9.0, with citrate buffer pH 6.0 as an alternative

• For difficult samples, extend retrieval time to 20-30 minutes at controlled 95-98°C

For frozen sections:

• Fix in cold acetone for 10 minutes or 4% paraformaldehyde for 15 minutes

• Permeabilize with 0.1-0.3% Triton X-100 if necessary

• Block with 5-10% normal serum from the same species as the secondary antibody

Dilution recommendations range from 1:20-1:200 for IHC applications, with optimal results typically achieved around 1:50 for human heart tissue samples . Extended primary antibody incubation (overnight at 4°C) often yields superior staining compared to shorter incubations at room temperature .

How can researchers address non-specific banding in ART5 Western blots?

Non-specific banding is a common challenge in ART5 Western blots that can be systematically addressed:

• Increase blocking stringency by using 5% BSA instead of non-fat milk, or consider adding 0.1% Tween-20 to reduce hydrophobic interactions

• Optimize primary antibody concentration – dilutions between 1:500-1:1000 typically provide the best signal-to-noise ratio for ART5 detection

• Implement gradient gel electrophoresis to better resolve proteins near the expected 35-40 kDa range of ART5

• Perform membrane washing steps with increased stringency (0.1-0.2% Tween-20 in TBS/PBS) and extended duration (4-5 washes of 10 minutes each)

If non-specific bands persist, consider using more specific detection methods such as:

• Immunoprecipitation followed by Western blotting to enrich for the target protein

• Comparison with knockout/knockdown controls to identify specific bands

• Using different ART5 antibodies targeting distinct epitopes to confirm authentic bands

What are the potential causes of variable ART5 staining intensity in immunohistochemistry?

Variable staining intensity in ART5 immunohistochemistry can result from multiple factors that require systematic troubleshooting:

For human lung cancer tissue, which shows variable ART5 expression, consecutive sections should be stained with both ART5 antibody and known cancer markers to correlate expression patterns . Additionally, implementing automated staining platforms can reduce batch-to-batch variation common in manual staining protocols.

How can researchers distinguish between true ART5 signals and artifacts in experimental data?

Distinguishing authentic ART5 signals from artifacts requires implementing multiple validation strategies:

• Confirm ART5 detection across multiple experimental platforms (e.g., both Western blot and IHC) using the same antibody

• Verify that the observed molecular weight matches the expected range (35-40 kDa for human samples, 43 kDa for mouse samples)

• Implement antibody absorption controls using recombinant ART5 protein to confirm signal specificity

• Compare staining/banding patterns using antibodies targeting different ART5 epitopes

Advanced validation approaches include correlation of protein detection with mRNA expression data from RT-PCR or RNA-seq experiments. For functional validation, researchers can perform enzyme activity assays specific to ART5's ADP-ribosyltransferase activity and correlate with antibody detection patterns. Lastly, subcellular localization studies should align with ART5's known secretory pathway targeting, with signals detected in the endoplasmic reticulum, Golgi apparatus, and extracellular space .