spag7 Antibody

What is SPAG7 and why is it significant for research?

SPAG7 (sperm associated antigen 7) is a widely expressed protein containing nuclear localization signals and an R3H domain that is predicted to bind single-stranded DNA or RNA in a sequence-specific manner . Despite its name suggesting sperm-specific expression, SPAG7 is expressed in virtually all tissues and cells in humans and mice .

The protein has gained significant research interest due to its essential role in embryonic development and energy homeostasis. SPAG7-deficient mice display intrauterine growth restriction, decreased birth weight, and develop obesity and glucose intolerance in adulthood . Furthermore, SPAG7 has been implicated in various disease states, including Asperger syndrome, parvovirus B19 infection, synovial sarcoma, azoospermia, PFAPA syndrome, squamous cell carcinoma, and oligoasthenozoospermia . These diverse associations make SPAG7 an important target for research across multiple fields.

What types of SPAG7 antibodies are available for research applications?

Based on current research tools, rabbit polyclonal antibodies against SPAG7 are the predominant type available for research applications. These include:

• Rabbit polyclonal antibodies that have been validated for Western blotting (WB), immunohistochemistry (IHC), and ELISA applications with demonstrated reactivity against human, mouse, and rat samples .

• Specific antibodies such as the Proteintech 16294-1-AP and 16294-1-PBS, which have been affinity-purified and validated across multiple applications .

These antibodies typically recognize the full SPAG7 protein with an observed molecular weight of 26-31 kDa, which aligns with the calculated molecular weight of 26 kDa (227 amino acids) .

What is the molecular structure and characteristics of SPAG7?

SPAG7 is a 227 amino acid protein with a calculated molecular weight of 26 kDa, though it typically appears at 26-31 kDa on Western blots . The protein contains:

• Two nuclear localization signals, indicating its primary location in the nucleus

• An R3H domain, which is predicted to bind single-stranded DNA or RNA in a sequence-specific manner

SPAG7 is highly conserved across species, with 97% amino acid sequence identity between humans and mice . This high degree of conservation suggests critical functional importance across mammalian species. The gene is located at GenBank accession number BC011934, gene ID 9552, and has the UniProt ID O75391 .

What are the validated applications for SPAG7 antibodies?

SPAG7 antibodies have been validated for several research applications:

Researchers should optimize antibody dilutions for their specific experimental conditions and sample types .

How should SPAG7 antibodies be stored and handled for optimal performance?

For optimal antibody performance and longevity:

• Store unconjugated SPAG7 antibodies at -80°C for long-term storage . Some antibody formulations may have different storage requirements, so always check manufacturer specifications.

• For antibodies in PBS buffer only (without preservatives), avoid repeated freeze-thaw cycles which can damage antibody structure and decrease activity.

• When working with the antibody, keep it on ice and return to appropriate storage promptly after use.

• For Western blotting applications, blocking with 5% milk in TBST (0.1%) for 1 hour at room temperature has been validated as effective .

• For primary antibody incubation in Western blotting, overnight incubation at 4°C followed by three washing steps with TBST (0.1%) is recommended .

Western Blotting Protocol:

• Snap-freeze tissue samples in liquid nitrogen and store at -80°C

• Homogenize tissues in ice-cold RIPA buffer

• Determine protein concentration using BCA protein assay

• Separate protein extracts on NuPAGE 4-20% Bis-Tris gels

• Transfer to PVDF membranes

• Block membranes for 1 hour at room temperature in TBST (0.1%) containing 5% milk

• Incubate with SPAG7 primary antibody (1:500-1:2000) overnight at 4°C

• Wash three times with TBST (0.1%)

• Incubate with HRP-conjugated secondary antibody for 1 hour at room temperature

• Wash thoroughly and visualize with chemiluminescent substrate

• Expected molecular weight: 26-31 kDa

Immunohistochemistry Protocol:

• Prepare sections from fixed tissues (typically formalin-fixed, paraffin-embedded)

• Perform antigen retrieval with TE buffer pH 9.0 (recommended) or citrate buffer pH 6.0 (alternative)

• Block endogenous peroxidase and non-specific binding

• Incubate with SPAG7 primary antibody (1:20-1:200)

• Apply appropriate detection system

• Counterstain, dehydrate, and mount

• Validated in human colon cancer tissue

How can SPAG7 antibodies be used to study metabolic disorders?

The recent discovery of SPAG7's role in metabolism and obesity makes SPAG7 antibodies valuable tools for investigating metabolic disorders:

• Tissue-specific expression analysis: Researchers can use SPAG7 antibodies in Western blotting and IHC to compare SPAG7 expression levels across adipose tissue, skeletal muscle, liver, and other metabolically relevant tissues in normal versus disease models .

• Developmental studies: As SPAG7-deficient mice show intrauterine growth restriction that leads to adult metabolic dysfunction, antibodies can be used to track SPAG7 expression throughout development and correlate with metabolic parameters .

• Intervention studies: Following therapeutic interventions in metabolic disease models, SPAG7 antibodies can help determine if treatments affect SPAG7 expression or activity.

• Co-immunoprecipitation: SPAG7 antibodies can be employed to identify protein interaction partners in metabolic tissues, potentially revealing mechanisms by which SPAG7 influences energy homeostasis.

The research showing that SPAG7 KO mice develop obesity not from hyperphagia but decreased energy expenditure suggests that SPAG7 plays a critical role in mitochondrial function and energy metabolism . Antibodies against SPAG7 provide an essential tool for dissecting these pathways.

What considerations are important when using SPAG7 antibodies in conjunction with ELISA kits?

When using SPAG7 ELISA kits or developing custom SPAG7 ELISAs using antibodies:

• Sample preparation: Human SPAG7 ELISA kits have been validated for serum, plasma, and other biological fluids. Proper sample collection, processing, and storage are critical for accurate results .

• Detection range and sensitivity: Commercial SPAG7 ELISA kits typically have a detection range of 200 to 3200 ng/L with a sensitivity of 9.38 ng/L. Ensure your samples fall within this range or prepare appropriate dilutions .

• Assay precision: When interpreting results, consider the intra-assay (CV <8%) and inter-assay (CV <10%) variation. Include appropriate controls to account for this variability .

• Antibody specificity: If developing custom ELISAs, select antibodies that have been validated for ELISA applications and show specificity for SPAG7 across relevant species. The high sequence conservation (97% between human and mouse) suggests many antibodies may cross-react across species .

• Protocol timing: Some commercial kits offer rapid protocols (e.g., 90-minute sandwich ELISA with a single wash step). Adhere strictly to the manufacturer's timing recommendations to ensure reliable results .

How can researchers troubleshoot non-specific binding or background issues with SPAG7 antibodies?

When facing specificity issues with SPAG7 antibodies:

• Antibody validation: Verify antibody specificity using positive and negative controls. For SPAG7, mouse ovary, brain, and skeletal muscle tissues have been validated as positive controls for Western blotting .

• Blocking optimization: Test different blocking agents (BSA, milk, commercial blockers) at various concentrations. For SPAG7 Western blots, 5% milk in TBST (0.1%) has been validated .

• Antibody dilution optimization: Titrate antibody concentrations to find the optimal signal-to-noise ratio. For SPAG7 antibodies, Western blot dilutions of 1:500-1:2000 and IHC dilutions of 1:20-1:200 are recommended starting points .

• Washing stringency: Increase washing duration or detergent concentration to reduce non-specific binding. For SPAG7 Western blots, three washing steps with TBST (0.1%) after primary antibody has been effective .

• Antigen retrieval methods: For IHC applications, compare different antigen retrieval methods. With SPAG7 antibodies, TE buffer pH 9.0 is recommended, though citrate buffer pH 6.0 can serve as an alternative .

• Knockout/knockdown validation: The ultimate specificity control is comparing wild-type to SPAG7 knockout or knockdown samples. The established SPAG7 KO mouse model provides an excellent negative control for antibody validation .

How might SPAG7 antibodies contribute to placental insufficiency and fetal development research?

SPAG7 antibodies represent valuable tools for investigating placental development and fetal growth restrictions:

• Placental junctional zone analysis: Research has shown that SPAG7 deficiency leads to abnormal development of the placental junctional zone. Immunohistochemistry with SPAG7 antibodies can help characterize the cellular and molecular changes in this critical placental region .

• Biomarker development: Since SPAG7 deficiency is associated with intrauterine growth restriction (IUGR), antibody-based detection of altered SPAG7 expression might serve as a potential biomarker for IUGR risk in clinical settings .

• Mechanistic studies: SPAG7 antibodies can help investigate the molecular mechanisms linking placental insufficiency to adult metabolic dysfunction, potentially addressing the developmental origins of health and disease (DOHaD) hypothesis .

• Therapeutic target validation: As our understanding of SPAG7's role in placental development advances, antibodies will be crucial for validating SPAG7 as a potential therapeutic target for pregnancy complications related to placental insufficiency.

The established link between SPAG7 deficiency, placental abnormalities, and subsequent metabolic disorders makes this protein a compelling focus for developmental and reproductive research.

What experimental considerations are important when studying SPAG7 in both nuclear and cytoplasmic compartments?

Given SPAG7's nuclear localization signals and potential nucleic acid binding function:

• Subcellular fractionation protocols: When analyzing SPAG7 expression by Western blotting, consider using subcellular fractionation to separate nuclear and cytoplasmic compartments. This can provide insight into SPAG7's localization under different conditions .

• Immunofluorescence optimization: For co-localization studies, antibody concentration and fixation methods should be optimized to preserve both nuclear structure and SPAG7 epitopes. Confocal microscopy can help determine precise subcellular localization.

• Function-specific detection: Since SPAG7 contains an R3H domain predicted to bind single-stranded DNA or RNA, researchers might need to investigate how nucleic acid binding affects antibody recognition. Consider using antibodies targeting different epitopes for comprehensive analysis .

• Post-translational modifications: Investigate whether SPAG7 undergoes post-translational modifications that might affect its localization, function, or antibody recognition. The observed molecular weight range (26-31 kDa) suggests potential modifications of the 26 kDa core protein .

• Sample preparation: Different fixation and permeabilization protocols may be required to optimize detection of nuclear versus potential cytoplasmic pools of SPAG7. Compare cross-linking fixatives (like formaldehyde) with precipitating fixatives (like methanol) to determine optimal conditions.

How can SPAG7 antibodies be used to investigate the protein's role in RNA/DNA binding and processing?

Given SPAG7's R3H domain and predicted role in nucleic acid binding:

• RNA/DNA immunoprecipitation (RIP/DIP): SPAG7 antibodies can be employed in RIP or DIP experiments to identify specific nucleic acid sequences that associate with SPAG7. This could provide insights into SPAG7's regulatory targets .

• Chromatin immunoprecipitation (ChIP): If SPAG7 associates with chromatin, ChIP using SPAG7 antibodies could reveal genomic binding sites and potential roles in transcriptional regulation.

• Proximity ligation assays: This technique can be used with SPAG7 antibodies to detect and visualize interactions between SPAG7 and other proteins involved in RNA processing or DNA regulation within cells.

• In situ hybridization combined with immunofluorescence: This approach can investigate co-localization of SPAG7 with specific RNA species, potentially revealing functional interactions.

• Functional domain analysis: Using antibodies targeting different regions of SPAG7 could help determine which domains are accessible in different functional states, particularly when the protein is bound to nucleic acids.

Understanding SPAG7's role in nucleic acid binding could provide significant insights into its function in normal development and disease states, particularly given its nuclear localization signals and conservation across species .

What are the most promising future directions for SPAG7 antibody-based research?

Based on current findings and gaps in knowledge, several promising research directions emerge:

• Metabolic disease mechanisms: Given SPAG7's role in energy homeostasis and obesity development, antibody-based studies investigating SPAG7's interaction partners in metabolic tissues could reveal novel therapeutic targets for metabolic disorders .

• Developmental programming: The "thrifty phenotype" observed in SPAG7 KO animals suggests SPAG7 as a key player in developmental programming of adult metabolism. Antibody-based temporal and spatial expression studies throughout development could elucidate critical windows for intervention .

• Mitochondrial dysfunction: SPAG7 KO animals display reduced exercise tolerance and muscle function due to impaired mitochondrial function. Antibody-based co-localization and co-immunoprecipitation studies could clarify SPAG7's direct or indirect roles in mitochondrial regulation .

• Clinical biomarker potential: Given SPAG7's involvement in various disease states, antibody-based detection methods might be developed into diagnostic or prognostic tools for conditions ranging from metabolic disorders to reproductive health issues .

• R3H domain function: Despite predictions that SPAG7's R3H domain binds nucleic acids, the specific targets and functional consequences remain largely unexplored. Antibodies that specifically recognize or block this domain could help characterize its role .

SPAG7 research represents an emerging field with significant implications across developmental biology, metabolism, and reproductive health. As our understanding of this multifunctional protein expands, antibody-based research tools will remain essential for unraveling its diverse biological roles.

What contradictions or unexplained phenomena exist in current SPAG7 research?

Several aspects of SPAG7 biology remain puzzling and warrant further investigation:

• Tissue-specific functions: Despite near-ubiquitous expression across tissues, SPAG7 deficiency produces phenotypes primarily affecting metabolism, growth, and potentially reproduction. This disconnect between broad expression and seemingly specific functions requires explanation .

• Molecular mechanism gap: While SPAG7 deficiency clearly affects metabolism and development, the molecular mechanisms linking SPAG7 to these processes remain largely uncharacterized. Antibody-based interactome studies might help bridge this gap .

• R3H domain targets: Though SPAG7's R3H domain is predicted to bind nucleic acids, the specific DNA or RNA targets remain unidentified. This fundamental aspect of SPAG7 function needs clarification through techniques like RIP-seq using validated antibodies .

• Evolutionary conservation paradox: The high degree of conservation (97% identity between mice and humans) suggests critical function, yet the protein's role has been largely understudied despite implications in multiple diseases .

• Developmental origins of adult phenotypes: The mechanism by which intrauterine SPAG7 deficiency programs adult metabolism represents a complex developmental biology question requiring sophisticated developmental timing studies with careful antibody-based expression analysis .