DOC2B Antibody

What is the optimal application range for DOC2B antibody in experimental designs?

DOC2B antibody (such as the 20574-1-AP) has been validated across multiple applications with specific recommended dilutions. For Western blot analysis, optimal results are typically achieved using dilutions between 1:1000-1:4000, while immunofluorescence applications require more concentrated preparations at 1:10-1:100 . This antibody has also demonstrated efficacy in co-immunoprecipitation experiments, though specific dilution requirements may vary based on experimental conditions. When designing experiments, it's important to note that published applications have successfully used this antibody for knockout/knockdown verification, Western blot, immunofluorescence, and co-immunoprecipitation studies .

The antibody has been validated in multiple tissue types and cell lines, including HEK-293 cells, mouse brain tissue, mouse kidney tissue for Western blot applications, and HepG2 and HeLa cells for immunofluorescence studies . When establishing new experimental systems, researchers should perform antibody titration to determine optimal concentrations for their specific application and sample type.

What are the key storage and handling considerations for maintaining DOC2B antibody functionality?

DOC2B antibody requires specific storage conditions to maintain its reactivity and specificity. The antibody should be stored at -20°C, where it remains stable for approximately one year after shipment . The storage buffer typically consists of PBS with 0.02% sodium azide and 50% glycerol at pH 7.3, which helps maintain antibody stability .

For long-term storage, aliquoting is generally unnecessary when storing at -20°C. Small volume preparations (20μl) may contain 0.1% BSA as a stabilizing agent . When handling the antibody, minimize freeze-thaw cycles and keep on ice during experiments. The liquid form of the antibody should not be subject to conditions that might promote protein denaturation such as extreme pH or temperatures. Researchers should consult specific product documentation, as storage recommendations may vary slightly between manufacturers.

Which species reactivity has been confirmed for DOC2B antibody and how should cross-species applications be validated?

The DOC2B antibody has confirmed reactivity with human, mouse, and rat samples, as demonstrated in both testing and citations in the scientific literature . When planning experiments with species not explicitly listed in validation data, researchers should conduct preliminary experiments to verify cross-reactivity.

For cross-species validation, a recommended approach includes:

• Running parallel Western blots with known positive controls from validated species alongside samples from the test species

• Confirming the expected molecular weight (46 kDa for DOC2B)

• Including appropriate negative controls (ideally knockout or knockdown samples)

• Performing peptide competition assays to verify specificity

The antibody recognizes the full DOC2B protein (double C2-like domains, beta) with both predicted and observed molecular weights of approximately 46 kDa . If working with species other than human, mouse, or rat, sequence homology analysis of the immunogen region can provide preliminary insight into potential cross-reactivity before experimental validation.

How can DOC2B antibody be effectively used to investigate calcium-dependent trafficking mechanisms?

DOC2B functions as a calcium sensor for vesicle priming, making its antibody valuable for investigating calcium-dependent trafficking mechanisms. Research has demonstrated that DOC2B readily traffics between the cytosol and plasma membrane during calcium influx events . To effectively study this process:

• Design experiments that combine calcium imaging with DOC2B immunolocalization:

  • Use calcium indicators (Fura-2, Fluo-4) to monitor intracellular calcium levels

  • Perform parallel immunofluorescence with DOC2B antibody (1:10-1:100 dilution)

  • Consider co-staining with membrane markers to assess translocation

• Implement calcium manipulation protocols:

  • Compare DOC2B localization at rest versus after stimulation with high K+ solution

  • Use calcium ionophores (ionomycin) or thapsigargin to artificially elevate calcium levels

  • Apply calcium chelators (BAPTA-AM) to block calcium-dependent trafficking

• Utilize mutant constructs alongside antibody detection:

  • The D218N/D220N (DN) mutant of DOC2B permanently localizes to the plasma membrane

  • Compare wild-type and mutant localization using the antibody to distinguish calcium-dependent from calcium-independent effects

This approach has been successfully applied in chromaffin cells, where researchers demonstrated that Doc2B traffics between cytosol and plasma membrane during reversible exposure to high K+ solution . The antibody can effectively distinguish between the diffuse cytosolic pattern of wild-type DOC2B at rest versus the membrane-associated pattern following calcium elevation.

What protocols are recommended for investigating DOC2B's role in β-cell protection against inflammatory damage?

Research has established that DOC2B plays a protective role in β-cells against inflammatory damage and proapoptotic stress . To investigate this function:

• Implement a combined approach using DOC2B antibody with apoptotic markers:

  • Western blot protocol: Use DOC2B antibody (1:1000 dilution) alongside apoptotic markers including cleaved caspase 3 (CC3), CHOP, PARP, and phospho-eIF2α

  • Compare control conditions with inflammatory cytokine treatment (TNF-α, IFN-γ, IL-1β) or thapsigargin exposure

• Establish appropriate model systems:

  • INS-1 832/13 β-cell culture treated with cytokines (10 ng/mL TNF-α, 100 ng/mL IFN-γ, 5 ng/mL IL-1β for 16h)

  • Doc2b knockout or heterozygous mouse models compared to wild-type

  • Inducible β-cell-specific Doc2b overexpressing transgenic mice

• Assess functional outcomes:

  • Measure glucose-stimulated insulin secretion (GSIS) in parallel with DOC2B levels

  • Quantify β-cell mass and apoptotic indices in pancreatic sections

  • Evaluate SNARE complex formation using co-immunoprecipitation with DOC2B antibody

This methodological approach has demonstrated that DOC2B enrichment enhances glucose-stimulated insulin secretion, increases SNARE activation, and prevents the appearance of apoptotic markers in response to cytokine stress . Researchers investigating similar protective mechanisms should incorporate both molecular (protein expression) and functional (insulin secretion) readouts in their experimental design.

How should researchers address potential discrepancies between DOC2B antibody detection and functional studies?

When investigating complex proteins like DOC2B that undergo trafficking and have multiple functional domains, researchers may encounter discrepancies between antibody detection and functional studies. To address these challenges:

• Implement complementary detection methods:

  • Compare fixed-cell immunofluorescence with live-cell imaging using EGFP-tagged DOC2B

  • Note that chemical fixation can cause calcium influx, artificially altering DOC2B localization

  • Combine antibody-based detection with functional readouts (calcium imaging, secretion assays)

• Consider post-translational modifications and protein interactions:

  • DOC2B's function is influenced by calcium binding, phospholipid interactions, and protein partnerships

  • Use phospho-specific antibodies if available to detect activity-dependent modifications

  • Perform co-immunoprecipitation to assess protein complex formation under different conditions

• Validate findings with genetic approaches:

  • Compare knockdown/knockout models with rescue experiments

  • Use domain-specific mutants (e.g., C2A vs. C2B domain mutations) to dissect functional contributions

  • Employ overexpression studies to determine if phenotypes scale with protein levels

A specific example from research demonstrates how the tandem C2 domains (C2AB) of DOC2B are sufficient to confer functional effects, including enhanced glucose-stimulated insulin secretion and protection against thapsigargin-induced β-cell apoptosis . When antibody detection indicates unexpected localization or expression patterns, researchers should confirm findings with domain-specific constructs and functional assays.

What is the recommended protocol for using DOC2B antibody in Western blot applications?

For optimal Western blot results with DOC2B antibody, follow this methodological approach:

• Sample preparation:

  • Prepare cell or tissue lysates in RIPA buffer with protease inhibitors

  • For tissues with documented DOC2B expression (brain, kidney, pancreatic β-cells), use 20-50 μg of total protein

  • Include positive controls: HEK-293 cells, mouse brain tissue, or mouse kidney tissue

• Gel electrophoresis and transfer:

  • Separate proteins on 10-12% SDS-PAGE gels (optimal for 46 kDa DOC2B protein)

  • Transfer to PVDF or nitrocellulose membranes using standard wet transfer protocols

• Antibody incubation:

  • Block membranes in 5% non-fat milk or BSA in TBST for 1 hour at room temperature

  • Dilute primary DOC2B antibody 1:1000-1:4000 in blocking buffer

  • Incubate overnight at 4°C with gentle agitation

  • Wash membranes 3x with TBST

  • Incubate with appropriate HRP-conjugated secondary antibody (anti-rabbit IgG)

  • Wash 3x with TBST

• Detection and analysis:

  • Develop using ECL reagents and image using an appropriate detection system

  • Expected molecular weight: 46 kDa

  • Verify specificity using knockout/knockdown controls when available

This protocol has been successfully implemented in studies examining DOC2B's role in β-cell protection, where researchers detected both endogenous DOC2B levels and expression of human DOC2B-DDK using the Proteintech antibody (catalog no. 20574-1-AP) at 1:1000 dilution .

What is the optimal methodology for immunofluorescence studies using DOC2B antibody?

For immunofluorescence detection of DOC2B in cellular contexts:

• Cell preparation:

  • Culture cells on glass coverslips to 60-80% confluence

  • Validated cell types include HepG2 and HeLa cells

  • For primary cells, follow tissue-specific isolation protocols (e.g., chromaffin cell isolation )

• Fixation and permeabilization:

  • Fix cells in 4% paraformaldehyde for 15 minutes at room temperature

  • Note: Chemical fixation can cause calcium influx, potentially altering DOC2B localization

  • Wash 3x with PBS

  • Permeabilize with 0.1% Triton X-100 in PBS for 10 minutes

  • Wash 3x with PBS

• Immunostaining:

  • Block in 5% normal goat serum in PBS for 1 hour at room temperature

  • Dilute DOC2B antibody 1:10-1:100 in blocking solution

  • Incubate overnight at 4°C in a humidified chamber

  • Wash 3x with PBS

  • Apply fluorophore-conjugated secondary antibody

  • For co-localization studies, consider double staining with vesicular markers like VAMP2/synaptobrevin-2

  • Counterstain nuclei with DAPI

  • Mount slides with anti-fade mounting medium

• Imaging and analysis:

  • Use confocal microscopy for precise localization studies

  • For trafficking studies, compare resting cells with stimulated conditions

  • Consider parallel live-cell imaging with EGFP-Doc2B constructs to validate findings

This approach has been validated in studies examining DOC2B localization and trafficking. Researchers investigating calcium-dependent trafficking should be aware that wild-type DOC2B readily traffics between cytosol and plasma membrane during calcium influx, while the DN-mutant (D218N/D220N) shows higher baseline membrane localization .

How can DOC2B antibody be utilized in co-immunoprecipitation studies to investigate protein interactions?

For investigating DOC2B protein interactions using co-immunoprecipitation:

• Lysate preparation:

  • Prepare cell/tissue lysates in non-denaturing lysis buffer (e.g., 50 mM Tris-HCl pH 7.4, 150 mM NaCl, 1% NP-40, with protease inhibitors)

  • Use tissues with documented DOC2B expression or cells overexpressing DOC2B

  • Clear lysates by centrifugation (14,000g, 10 minutes, 4°C)

• Immunoprecipitation:

  • Pre-clear lysate with protein A/G beads for 1 hour at 4°C

  • Incubate 500-1000 μg of pre-cleared lysate with 2-5 μg DOC2B antibody overnight at 4°C with rotation

  • Add protein A/G beads and incubate for 2-4 hours at 4°C

  • Wash beads 4-5 times with lysis buffer

  • Elute bound proteins by boiling in SDS sample buffer

• Analysis of interacting partners:

  • Separate immunoprecipitated proteins by SDS-PAGE

  • Perform Western blot analysis for potential interacting partners, including:

    • SNARE proteins (syntaxin-4, SNAP-25, VAMP2)

    • Munc18 proteins

    • Other trafficking regulators

• Controls to include:

  • IgG control (same species as DOC2B antibody)

  • Input sample (10% of lysate used for IP)

  • Reverse co-IP where appropriate (IP with antibody against suspected interacting partner)

This methodology has been successfully applied to demonstrate that DOC2B serves as a scaffolding platform for concurrent binding of multiple proteins, including Munc18 proteins that promote insulin release . When performing co-IP studies, researchers should consider both constitutive and calcium-dependent interactions, as DOC2B's binding properties can change with calcium levels.

How should researchers interpret DOC2B expression patterns across different tissues and experimental conditions?

When analyzing DOC2B expression patterns:

• Expected tissue distribution:

  • DOC2B is documented in multiple tissues including brain, kidney, and pancreatic β-cells

  • Expression levels may vary significantly between tissues

  • Consider relative quantification against housekeeping genes appropriate for each tissue

• Subcellular localization patterns:

  • At resting calcium levels: primarily cytosolic distribution

  • After calcium elevation: increased plasma membrane association

  • The D218N/D220N mutant shows constitutive membrane localization

• Data interpretation framework:

  • Compare expression levels across experimental conditions using densitometry

  • Normalize to total protein or housekeeping genes

  • For localization studies, quantify cytosolic versus membrane fractions

  • Consider calcium levels when interpreting localization data

• Common interpretation challenges:

  • Background staining in immunofluorescence may be mistaken for specific signal

  • Multiple bands in Western blot could indicate isoforms, degradation products, or non-specific binding

  • Changes in localization without changes in expression may reflect functional regulation

Research has demonstrated that DOC2B expression and function are particularly important in pancreatic β-cells, where it protects against diabetogenic and proapoptotic stress . When interpreting DOC2B expression data, researchers should consider both the absolute levels of expression and the subcellular distribution, as both can impact the protein's functional role.

What are the common challenges in DOC2B antibody studies and how can they be addressed?

Researchers working with DOC2B antibody may encounter several technical challenges:

• Specificity concerns:

  • Challenge: Non-specific bands in Western blot analysis

  • Solution: Validate specificity using knockout/knockdown controls

  • Include peptide competition assays to confirm binding specificity

  • Compare results across multiple antibody sources if available

• Signal-to-noise issues in immunofluorescence:

  • Challenge: High background or weak specific signal

  • Solution: Optimize antibody concentration (test range from 1:10-1:100)

  • Increase blocking stringency (5-10% serum, longer blocking times)

  • Include negative controls (secondary antibody only, non-expressing tissues)

• Calcium-dependent localization artifacts:

  • Challenge: Fixation can cause calcium influx, altering DOC2B localization

  • Solution: Compare fixed samples with live-cell imaging of fluorescently tagged DOC2B

  • Use rapid fixation protocols to minimize calcium-induced trafficking

  • Consider calcium chelators during fixation process

• Quantification challenges:

  • Challenge: Accurately measuring DOC2B levels or distribution

  • Solution: Use digital image analysis with appropriate controls

  • For membrane/cytosol distribution, establish clear criteria for classification

  • Include internal standards for cross-experiment comparisons

By addressing these common challenges methodically, researchers can improve the reliability and reproducibility of their DOC2B antibody-based studies. The combination of appropriate controls, optimization of protocols, and awareness of potential artifacts is essential for accurate data interpretation.

How is DOC2B antibody being used to investigate the protein's role in diabetes and β-cell function?

DOC2B antibody has become instrumental in advancing our understanding of diabetes mechanisms:

• Methodological approaches in diabetes research:

  • Detection of DOC2B in pancreatic sections and isolated islets

  • Combined analysis with markers of β-cell function and stress

  • Correlation of DOC2B levels with insulin secretion capacity

• Key experimental models where DOC2B antibody provides critical insights:

  • Doc2b+/− knockout mice: Show severe response to multiple-low-dose streptozotocin (MLD-STZ), with increased β-cell apoptosis and reduced β-cell mass

  • Inducible β-cell-specific Doc2b-overexpressing transgenic (βDoc2b-dTg) mice: Demonstrate improved glucose tolerance and resistance to STZ-induced disruption

  • Cell culture models: INS-1 832/13 β-cells treated with inflammatory cytokines

• Functional readouts paired with antibody detection:

  • Glucose-stimulated insulin secretion (GSIS)

  • SNARE complex formation and activation

  • Apoptotic marker expression (cleaved caspase 3, CHOP, PARP)

Research has established that Doc2b enrichment in β-cells enhances glucose-stimulated insulin secretion, increases SNARE activation, and prevents the appearance of apoptotic markers in response to cytokine stress and thapsigargin . These findings suggest that DOC2B may represent a therapeutic target for protecting functional β-cell mass. The antibody enables researchers to correlate protective effects with protein expression levels and localization in different experimental contexts.

What methodological approaches are recommended for investigating DOC2B's role in vesicle priming and calcium sensing?

To investigate DOC2B's function in vesicle priming and calcium sensing:

• Electrophysiological approaches combined with immunocytochemistry:

  • Capacitance measurements to assess vesicle fusion

  • Parallel amperometry to detect catecholamine release

  • Immunostaining to correlate DOC2B levels and distribution with functional readouts

• Calcium manipulation protocols:

  • Use of calcium uncaging to trigger rapid calcium elevation

  • Maintenance of defined basal calcium levels (e.g., ~800-900 nM) to maximize priming

  • Application of calcium indicators to correlate DOC2B localization with calcium levels

• Mutant analysis approach:

  • Wild-type DOC2B: Shuttles between cytosol and membrane in calcium-dependent manner

  • D218N/D220N (DN) mutant: Shows constitutive membrane localization

  • C2AB domain peptide: Contains tandem C2A and C2B domains, sufficient to confer beneficial effects

• Quantification methods:

  • Analysis of exocytotic burst components (first 0.5s after stimulation)

  • Measurement of sustained release (0.5-5s after stimulation)

  • Integration of amperometric signals to confirm capacitance measurements

Research has established that DOC2B plays distinct roles in sequential priming steps, with expression increasing the burst of secretion while decreasing sustained release . These findings highlight the importance of temporal resolution in experimental approaches, as DOC2B's effects may differ between early and late phases of exocytosis.

What are the key considerations for researchers designing experiments with DOC2B antibody?

Researchers planning studies with DOC2B antibody should consider these essential points to ensure successful experimental outcomes:

• Application-specific optimization:

  • Western blot applications: Use 1:1000-1:4000 dilution range

  • Immunofluorescence studies: Use 1:10-1:100 dilution range

  • Always perform antibody titration for new experimental systems

• Methodological controls:

  • Include positive controls: HEK-293 cells, mouse brain tissue, mouse kidney tissue

  • Implement negative controls: knockout/knockdown samples when available

  • Use subcellular fractionation to distinguish membrane vs. cytosolic pools

• Functional context considerations:

  • DOC2B functions and localization are calcium-dependent

  • Consider the dynamic nature of the protein when designing fixation protocols

  • Pair antibody detection with functional readouts appropriate to the research question

• Data interpretation framework:

  • Expected molecular weight: 46 kDa

  • Anticipate potential changes in localization with experimental manipulations

  • Consider both expression levels and distribution patterns in analyses