Recombinant Human Probetacellulin (BTC)

What is Recombinant Human Probetacellulin (BTC) and what is its significance in research?

Recombinant Human Probetacellulin (BTC) is a full-length protein that belongs to the cytokine family. It is a precursor protein that is cleaved to produce the mature Betacellulin, which functions as a growth factor. BTC has significant research value as it has been implicated as a possible cancer biomarker in various studies and has been associated with several cancer types, including ovarian cancer . The protein has a molecular weight of approximately 18.6 kDa and is typically produced in expression systems such as yeast for research applications . The significance of BTC in research stems from its cell proliferation-inducing properties and its potential role in cancer pathophysiology, making it valuable for both basic cellular research and clinical biomarker development studies.

What are the structural characteristics and sequence details of Human Probetacellulin?

Human Probetacellulin has a specific amino acid sequence that contributes to its biological functions. The mature protein sequence as documented in recombinant versions includes: DGNSTRSPETNGLLCGDPEENCAATTTQSKRKGHFSRCPKQYKHYCIKGRCRFVVAEQTPSCVCDEGYIGARCERVDLFYLRGDRGQILVICLIAVMVVFIILVIGVCTCCHPLRKRRKRKKKEEEMETLGKDITPINEDIEETNIA . The protein is identified with UniProtKB accession number P35070 and is also known by synonyms such as BTC and Probetacellulin . The functional expression range typically spans amino acids 32-178, representing the full length of the mature protein . Structurally, BTC contains specific domains including a signal sequence, a propeptide region, and a mature growth factor domain with characteristic cysteine residues that form disulfide bonds critical for its three-dimensional structure and biological activity.

How is Recombinant Human Probetacellulin produced and purified for research applications?

Recombinant Human Probetacellulin for research applications is commonly produced using various expression systems. According to the search results, it can be produced in yeast expression systems, resulting in a high-quality recombinant protein with greater than 90% purity as determined by SDS-PAGE . Other manufacturers like R&D Systems produce animal-free versions in specialized facilities to avoid potential contaminants from animal sources .

The production typically involves the following methodology:

• Gene cloning into an appropriate expression vector

• Transformation into the chosen expression system (yeast, mammalian cells, etc.)

• Protein expression under optimized conditions

• Cell harvesting and protein extraction

• Purification through chromatographic methods, often utilizing affinity tags such as His-tags

• Quality control testing including SDS-PAGE and functional bioassays

The final product may be provided in either liquid form (typically in Tris/PBS-based buffer with 5-50% glycerol) or as a lyophilized powder (with Tris/PBS-based buffer containing 6% Trehalose, pH 8.0) . Researchers should verify the expression system and purification strategy depending on their specific experimental requirements.

What are the recommended storage and handling conditions for Recombinant Human Probetacellulin?

For optimal stability and activity of Recombinant Human Probetacellulin, specific storage and handling protocols should be followed. The recommended storage conditions include maintaining the protein at -20°C to -80°C upon receipt, with proper aliquoting for multiple use to prevent protein degradation . Working aliquots can be stored at 4°C for up to one week, but repeated freeze-thaw cycles should be strictly avoided as they can significantly degrade protein structure and activity .

For reconstitution of lyophilized BTC, the vial should be briefly centrifuged prior to opening to bring all contents to the bottom. The protein should then be reconstituted in deionized sterile water to a concentration of 0.1-1.0 mg/mL . Addition of glycerol to a final concentration of 5-50% is recommended for long-term storage (with 50% being the default recommendation) . This glycerol addition helps prevent protein denaturation during freezing processes. Proper handling procedures ensure that experimental results remain consistent and reproducible across studies, which is crucial for comparative analyses in research settings.

How can Recombinant Human Probetacellulin be used in cell proliferation assays?

Recombinant Human Probetacellulin can be effectively employed in cell proliferation assays to evaluate its biological activity and to study cellular responses to growth factor stimulation. According to the search results, BTC demonstrates measurable activity in cell proliferation assays using Balb/3T3 mouse embryonic fibroblast cells with an ED50 (effective dose for 50% response) typically ranging from 0.100-1.50 ng/mL . This demonstrates its potent biological activity even at low concentrations.

Methodology for cell proliferation assays using BTC typically includes:

• Cell preparation: Culture the appropriate responsive cell line (e.g., Balb/3T3 fibroblasts) in suitable growth medium

• Cell seeding: Plate cells at optimal density in multi-well plates and allow attachment

• Starvation: Serum-starve cells for 12-24 hours to synchronize cell cycles

• Treatment: Apply serial dilutions of BTC (typically ranging from 0.01-10 ng/mL)

• Incubation: Allow cells to proliferate for 24-72 hours

• Readout: Measure proliferation using methods such as MTT/XTT assays, thymidine incorporation, or cell counting

When comparing different grades or lots of BTC, consistent bioactivity is crucial for experimental reproducibility. The search results indicate that Animal-Free (BT-BTC-AFL), GMP (BT-BTC-GMP), and RUO (BT-BTC) grades of Recombinant Human Betacellulin show equivalent bioactivity in the cell proliferation assay using Balb/3T3 cells , demonstrating lot-to-lot consistency that is essential for reliable research outcomes.

What challenges exist in detecting Recombinant Human Probetacellulin in plasma samples?

Detection of Recombinant Human Probetacellulin in plasma samples presents significant analytical challenges due to its low abundance. According to the search results, BTC concentration in human plasma is approximately 4 ng/mL , placing it in the range of low-abundance plasma proteins. Additionally, BTC has not been previously detected in human plasma by conventional mass spectrometry (MS) methods according to PeptideAtlas , highlighting the technical difficulties in its detection.

The following methodological approaches have been developed to overcome these challenges:

• Recombinant Protein Spectral Library (rPSL) approach:

  • Creation of a spectral library using purified recombinant proteins

  • Coupling with SWATH-MS (Sequential Window Acquisition of all Theoretical Mass Spectra) analysis

  • Application of high-stringency protein identification criteria (> 2 peptides, non-nested, uniquely-mapping peptides of > 9 amino acids length)

This innovative approach has demonstrated success in detecting previously undetectable proteins, including BTC . In a comparative study, the rPSL SWATH methodology identified 32 proteins (including BTC) in plasma samples, while traditional DDA-MS (Data-Dependent Acquisition) using MARS-depleted and post-digestion peptide fractionated plasmas only identified 12 of these proteins . This significant improvement in detection capability is particularly valuable for biomarker discovery and validation studies.

Researchers studying BTC in plasma should consider:

• Using highly sensitive detection methods like rPSL SWATH

• Applying proper sample preparation techniques to reduce interference from high-abundance proteins

• Implementing stringent data filtering and false discovery rate (FDR) calculations

• Validating MS findings with orthogonal methods like immunoassays

What is the role of Recombinant Human Probetacellulin as a potential cancer biomarker?

Recombinant Human Probetacellulin has emerged as a potential cancer biomarker across multiple cancer types. Based on the search results, BTC has been specifically associated with ovarian cancer . The protein's involvement in cellular growth and proliferation pathways provides a biological rationale for its potential role in cancer development and progression.

The evidence supporting BTC as a cancer biomarker includes:

• Altered expression levels in cancer tissues compared to normal tissues

• Detectable presence in plasma samples from cancer patients

• Inclusion in panels of cancer-associated proteins selected for biomarker discovery studies

The methodological approach for investigating BTC as a cancer biomarker typically involves:

• Detection of BTC in patient samples (plasma, tissue, etc.) using sensitive methods like rPSL SWATH-MS or immunoassays

• Correlation of BTC levels with clinical parameters (disease stage, prognosis, treatment response)

• Comparison between cancer patients and healthy controls

• Integration with other biomarkers for improved diagnostic performance

A notable study described in the search results included BTC among 36 cancer-associated proteins used to generate a recombinant protein spectral library (rPSL) for improved detection of low-abundance proteins in colorectal cancer patient plasmas . This approach successfully identified BTC in plasma samples, despite its low abundance, demonstrating the feasibility of detecting this potential biomarker in clinical specimens.

Research on BTC as a cancer biomarker is still evolving, with ongoing studies exploring its utility in various cancer types, its prognostic value, and its potential role in monitoring treatment response.

What are the critical factors for successful reconstitution of lyophilized Recombinant Human Probetacellulin?

Successful reconstitution of lyophilized Recombinant Human Probetacellulin is critical for maintaining protein activity and ensuring experimental reproducibility. Based on the search results, several key methodological factors should be considered during the reconstitution process.

First, the vial containing lyophilized BTC should be briefly centrifuged prior to opening to bring all contents to the bottom, preventing potential loss of material . The recommended reconstitution involves using deionized sterile water to achieve a final concentration of 0.1-1.0 mg/mL . The quality of water used is critical—it should be sterile and free from contaminants that might affect protein stability or introduce experimental variables.

For long-term storage, the addition of glycerol to a final concentration of 5-50% is recommended, with 50% being the default recommendation for optimal preservation . This glycerol addition is crucial as it:

• Prevents protein denaturation during freeze-thaw cycles

• Reduces ice crystal formation that can damage protein structure

• Maintains protein in solution at low temperatures

The buffer composition of lyophilized BTC typically includes Tris/PBS-based buffer with 6% Trehalose at pH 8.0 . This specific formulation provides optimal conditions for maintaining protein stability during the lyophilization and reconstitution processes. The presence of Trehalose, a disaccharide, serves as a cryoprotectant that helps preserve protein structure during freeze-drying.

Researchers should avoid repeated freeze-thaw cycles, as these can significantly degrade the protein and reduce its biological activity . Instead, reconstituted BTC should be properly aliquoted into single-use volumes before storage at -20°C or -80°C for long-term preservation.

How can researchers validate the biological activity of Recombinant Human Probetacellulin?

Validating the biological activity of Recombinant Human Probetacellulin is essential to ensure that experimental results are reliable and reproducible. Several methodological approaches can be employed for this validation:

• Cell Proliferation Assays:
  The primary method for validating BTC activity is through cell proliferation assays using responsive cell lines. According to the search results, Balb/3T3 mouse embryonic fibroblast cells are commonly used for this purpose . The effective dose (ED50) for BTC-induced proliferation typically ranges from 0.100-1.50 ng/mL . A properly active BTC preparation should demonstrate dose-dependent stimulation of cell proliferation within this concentration range.

• Comparative Analysis:
  Comparing the activity of different preparations or lots of BTC is crucial for experimental consistency. The search results indicate that equivalent bioactivity can be demonstrated between different grades of Recombinant Human Betacellulin (GMP, Animal-Free, and RUO grades) when measured in cell proliferation assays . This approach allows researchers to validate new lots or preparations against established standards.

• Protein Quality Assessment:
  SDS-PAGE analysis under both reducing and non-reducing conditions can provide valuable information about protein integrity. According to the search results, properly prepared BTC should show bands at 12-15 kDa under SDS-PAGE with Coomassie blue staining . Differences in migration patterns between reducing and non-reducing conditions can indicate proper disulfide bond formation, which is critical for biological activity.

• Receptor Binding Assays:
  Although not explicitly mentioned in the search results, receptor binding assays represent another approach to validate BTC activity. These assays measure the ability of BTC to bind to its receptors (primarily members of the ErbB family) using techniques such as surface plasmon resonance or competitive binding assays.

Implementing these validation methods ensures that the recombinant BTC used in experiments possesses the expected biological activity, which is essential for generating reliable and reproducible research outcomes.

What methodological considerations are important when using Recombinant Human Probetacellulin in mass spectrometry-based biomarker studies?

When utilizing Recombinant Human Probetacellulin in mass spectrometry (MS)-based biomarker studies, several methodological considerations are critical for successful detection and quantification. According to the search results, BTC is among the proteins not previously detected in human plasma by conventional MS methods according to PeptideAtlas , highlighting the challenges in its analysis.

The following methodological approaches have proven effective for BTC detection in complex biological samples:

• Spectral Library Generation:
  Creating a recombinant protein spectral library (rPSL) using purified recombinant BTC significantly improves detection capabilities. This approach involves tryptic digestion of the recombinant protein followed by MS analysis to generate reference spectra . The resulting spectral library provides a high-quality reference for subsequent analyses of complex samples.

• SWATH-MS Analysis:
  Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH-MS) coupled with an rPSL has demonstrated superior performance in detecting low-abundance proteins like BTC compared to conventional Data-Dependent Acquisition (DDA) approaches . The methodology involves:

  • Using a TripleTOF mass spectrometer for data acquisition

  • Implementing a 60-minute LC gradient (5-35% mobile phase B) at 600nl/min

  • Performing retention time calibration using indexed retention time (iRT)

  • Setting appropriate transition settings for targeted peptides

• Data Filtering and FDR Control:
  Proper data filtering is essential to ensure reliable identification:

  • Applying a 1% false discovery rate (FDR) cutoff (Q value ≤ 0.01)

  • Using a dot product (dotP) cutoff of 0.6 to measure correlation between observed and measured spectra

  • Removing standard RT calibration peptides and peptides with ≥2 missed cleavages

  • Filtering out modified peptides except for carbamidomethylated cysteine and oxidized methionine

• Validation Criteria:
  For high-confidence protein identification, stringent criteria should be applied:

  • Identification based on ≥2 non-nested, uniquely-mapping peptides

  • Peptide length of >9 amino acids

  • Limited to <1 missed cleavage

  • Consistent detection across multiple replicates

By implementing these methodological considerations, researchers can significantly improve the detection and quantification of BTC in complex biological samples, particularly in biomarker studies where low-abundance proteins are often of great interest.

How does Recombinant Human Probetacellulin compare to other EGF family growth factors in research applications?

Recombinant Human Probetacellulin (BTC) belongs to the epidermal growth factor (EGF) family, which includes several related growth factors with distinct and overlapping functions. While the search results don't provide direct comparative data with other EGF family members, we can examine the unique properties of BTC that differentiate it in research applications.

A key distinction of BTC in research applications is its emerging role as a potential cancer biomarker. Unlike some better-characterized EGF family members, BTC has not been previously detected in human plasma by conventional mass spectrometry methods , making it a potentially novel biomarker candidate. Its plasma concentration of approximately 4 ng/mL places it in the category of low-abundance proteins, requiring specialized detection methods.

For researchers planning comparative studies between BTC and other EGF family members, the following methodological considerations are important:

• Receptor specificity and signaling pathway activation should be compared under standardized conditions

• Dose-response relationships should be established across multiple cellular contexts

• Identical experimental conditions should be maintained when comparing biological activities

• The same detection and quantification methods should be applied across all proteins being compared

The choice between BTC and other EGF family members for specific research applications should be guided by:

• The specific receptors and signaling pathways under investigation

• The cellular context of the study

• The availability of high-quality recombinant proteins with consistent activity

• The specific disease or physiological process being modeled

What considerations are important when designing experiments with Recombinant Human Probetacellulin across different cell types?

When designing experiments with Recombinant Human Probetacellulin across different cell types, several methodological considerations are crucial for generating reliable and interpretable results.

First, receptor expression profiling is essential since the biological effects of BTC are mediated through binding to specific receptors, primarily members of the ErbB family. Different cell types express varying levels of these receptors, which significantly impacts their responsiveness to BTC stimulation. Before conducting experiments, researchers should verify receptor expression through techniques such as Western blotting, flow cytometry, or RT-PCR to ensure the cell types under investigation express the relevant receptors.

The experimental readout selection should align with the biological processes being studied. While cell proliferation is a common readout for BTC activity , other cellular responses such as migration, differentiation, or specific signaling pathway activation may be more relevant depending on the research question. Multiple readouts should be considered to capture the full spectrum of BTC effects.

Timing considerations are also important as different cell types may exhibit different temporal response patterns to BTC stimulation. Time-course experiments should be conducted to determine optimal stimulation periods for the specific cellular responses being measured.

Finally, proper controls are essential for experimental validation:

• Positive controls using well-characterized growth factors with known effects on the cell type

• Negative controls including vehicle-only treatments

• Receptor inhibition controls using specific antagonists or neutralizing antibodies

• Heat-inactivated BTC controls to confirm that observed effects are due to the specific protein activity rather than contaminants

By systematically addressing these considerations, researchers can design robust experiments that accurately characterize the effects of BTC across different cellular contexts.

What are the optimal experimental designs for studying Recombinant Human Probetacellulin as a biomarker in cancer research?

Designing optimal experiments for studying Recombinant Human Probetacellulin as a biomarker in cancer research requires careful consideration of sample collection, processing methods, detection techniques, and data analysis approaches. Based on the search results and broader research principles, the following methodological considerations are recommended:

1. Cohort Selection and Sample Collection:

• Include balanced groups of cancer patients (at various disease stages) and healthy controls

• Consider longitudinal sampling to track BTC levels over disease progression or treatment

• Standardize sample collection procedures (time of day, fasting status, etc.)

• Collect multiple biospecimen types where possible (plasma, serum, tissue, etc.)

2. Sample Processing and Storage:

• Process samples within a standardized timeframe to minimize pre-analytical variables

• Use consistent protocols for plasma/serum separation

• Aliquot samples to avoid repeated freeze-thaw cycles

• Store at -80°C for long-term stability

3. Detection and Quantification Methods:
The search results highlight specific approaches for BTC detection in plasma:

• Recombinant Protein Spectral Library (rPSL) coupled with SWATH-MS has successfully detected BTC in plasma samples despite its low abundance (4 ng/mL)

• This approach outperformed traditional DDA-MS methods, identifying BTC when conventional approaches failed

• Apply high-stringency identification criteria (>2 peptides, non-nested, uniquely-mapping peptides of >9 amino acids length)

4. Experimental Design Considerations:

• Include technical replicates (minimum 3) to assess method reproducibility

• Incorporate quality control samples for normalization across batches

• Consider multiplexed approaches to measure BTC alongside other potential biomarkers

• Include spike-in standards for quantification

5. Validation Approaches:

• Confirm MS findings with orthogonal methods (e.g., ELISA, Western blot)

• Validate in independent cohorts

• Correlate BTC levels with clinical parameters and outcomes

6. Data Analysis and Interpretation:

• Apply appropriate statistical methods for biomarker evaluation

• Assess sensitivity, specificity, and area under ROC curve

• Consider BTC in the context of multimarker panels

• Correlate findings with histopathological and molecular data

The study described in the search results provides a valuable methodological framework, demonstrating how rPSL SWATH-MS can be applied to detect low-abundance proteins, including BTC, in plasma samples from colorectal cancer patients . This approach allowed the identification of BTC in non-depleted plasma, which had not been previously detected using conventional MS methods . Adapting and optimizing this methodology offers a promising approach for investigating BTC as a cancer biomarker.

What emerging technologies might enhance detection and characterization of Recombinant Human Probetacellulin in complex biological samples?

The detection and characterization of Recombinant Human Probetacellulin in complex biological samples presents significant challenges due to its low abundance. Based on the search results and emerging trends in protein analysis, several promising technologies could enhance future research in this area:

• Advanced Mass Spectrometry Approaches:
  The search results already highlight the success of the recombinant protein spectral library (rPSL) coupled with SWATH-MS for detecting BTC in plasma samples . This approach could be further enhanced through:

  • Targeted proteomics using Parallel Reaction Monitoring (PRM) for improved sensitivity

  • Ion mobility-mass spectrometry for enhanced separation of complex mixtures

  • Novel enrichment strategies specifically designed for low-abundance proteins

  • Advanced data-independent acquisition (DIA) methods beyond SWATH

• Proximity-Based Detection Methods:
  Proximity ligation or extension assays could provide highly sensitive detection of BTC through:

  • Dual recognition using antibody pairs to increase specificity

  • Signal amplification through DNA polymerase activity

  • Localized detection in tissue samples to map expression patterns

• Single-Molecule Detection Technologies:
  Emerging single-molecule detection platforms could potentially detect BTC at extremely low concentrations:

  • Single-molecule arrays (Simoa) technology

  • Optical detection of individual labeled molecules

  • Nanopore-based protein sensing

• Aptamer-Based Technologies:
  Developing specific aptamers against BTC could enable:

  • Highly selective capture from complex samples

  • Combination with electrochemical detection for quantification

  • Integration into point-of-care testing platforms

• Computational and Bioinformatic Approaches:
  The search results describe several bioinformatic strategies for improving BTC detection , which could be enhanced through:

  • Advanced machine learning algorithms for spectral matching

  • Improved retention time prediction for more accurate peak identification

  • Novel data filtering approaches to reduce false positives while maintaining sensitivity

  • Integration of multiple -omics datasets for contextual interpretation

These emerging technologies hold promise for overcoming the current limitations in detecting and characterizing BTC in complex biological samples, potentially enabling more comprehensive studies of its role as a biomarker and its biological functions in normal and disease states.

What is the potential for developing standardized assays for Recombinant Human Probetacellulin in clinical research?

The development of standardized assays for Recombinant Human Probetacellulin in clinical research represents an important goal, particularly given its potential as a cancer biomarker. Based on the search results and broader principles of assay development, several methodological considerations are important for establishing such standardized approaches:

1. Reference Material Standardization:
A critical first step is establishing well-characterized reference materials:

• Purified recombinant BTC with defined activity (such as the animal-free preparation described in search result )

• Consistent production methods to ensure lot-to-lot reproducibility

• Stability testing under various storage conditions

• International reference standards when possible

2. Mass Spectrometry-Based Assay Development:
The search results highlight successful detection of BTC using rPSL SWATH-MS , which could be developed into a standardized assay through:

• Selection of optimal peptide targets for MRM/PRM assays

• Development of stable isotope-labeled internal standards

• Establishment of standardized sample preparation protocols

• Interlaboratory validation studies

3. Immunoassay Development:
While not explicitly mentioned in the search results, immunoassay development would be valuable:

• Generation and validation of specific antibodies against BTC

• Development of sandwich ELISA or other immunoassay formats

• Optimization for various sample types (plasma, serum, tissue extracts)

• Sensitivity enhancement methods to detect low ng/mL concentrations

4. Assay Validation Criteria:
Standardized assays would require validation according to established guidelines:

• Analytical sensitivity (limit of detection, limit of quantification)

• Analytical specificity (cross-reactivity testing)

• Precision (intra-assay and inter-assay variability)

• Accuracy (recovery experiments)

• Linearity across the calibration range

• Sample stability under various conditions

5. Clinical Validation:
Beyond analytical validation, clinical validation would be essential:

• Establishment of reference ranges in healthy populations

• Assessment of biological variability

• Correlation with disease states or outcomes

• Comparison with existing biomarkers

6. Quality Control Procedures:
Standardized quality control procedures would ensure reliable results:

• Internal quality control materials at multiple concentrations

• External quality assessment programs

• Standard operating procedures for all analytical steps

• Regular calibration verification

The development of such standardized assays would significantly advance BTC research by enabling reliable comparison of results across different studies and laboratories, ultimately facilitating its evaluation as a clinical biomarker and research tool.