TBCB Human

Tubulin Folding Cofactor B Human Recombinant
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Description

Microtubule Regulation

TBCB acts as a chaperone for β-tubulin, ensuring proper folding into α/β heterodimers. It prevents dissociation of tubulin monomers, stabilizing microtubule dynamics .

Regulation of Axonal Growth

Studies suggest TBCB negatively regulates axonal growth, modulating cytoskeletal organization during neuronal development .

Prognostic Biomarker

Elevated TBCB expression in AML correlates with poor outcomes:

Clinical FeatureHigh TBCB ExpressionLow TBCB Expression
WBC Count>20 × 10⁹/L (p < 0.01)≤20 × 10⁹/L
BM Blasts>20% (p < 0.01)≤20%
FLT3 MutationHigher frequency (p < 0.01)Lower frequency

Immune Evasion and Drug Sensitivity

  • NK Cell Infiltration: High TBCB correlates with increased CD56bright NK cells in the tumor microenvironment .

  • Drug Responses:

    • Sensitive to: ATRA, midostaurin.

    • Resistant to: Cytarabine, dasatinib, imatinib .

Gene Expression and Pathway Activation

  • Upregulated in AML: TBCB mRNA levels are significantly higher in AML patients vs. healthy donors (p < 0.001) .

  • Immune-Related Pathways: Enriched in high-TBCB AML, including NK cell inhibitory receptor signaling .

Experimental Validation

  • In Vitro Studies: TBCB knockdown in AML cell lines induces apoptosis and cell cycle arrest .

  • ROC Analysis: TBCB distinguishes AML from normal samples (AUC = 0.731) .

Comparative Analysis with Other TBC Proteins

FeatureTBCBTBCE (Example)
DomainCAP-GlyCofactor E domain
FunctionTubulin folding, axonal regulationα-tubulin binding, cytoskeleton stability
Disease RoleAML progressionNeurodegenerative disorders (e.g., hereditary spastic paraplegia)

Unresolved Questions

  • Mechanism of Immune Modulation: How TBCB interacts with NK cells to evade immune detection.

  • Therapeutic Targeting: Developing inhibitors to suppress TBCB in AML while preserving microtubule function.

Methodological Limitations

  • Heterogeneity in AML Subtypes: TBCB’s role may vary across FAB classifications (e.g., M0 vs. M3) .

  • Protein Stability: Recombinant TBCB requires storage at -20°C to prevent degradation .

Product Specs

Introduction
TBCB, a member of the Microtubules family, plays a crucial role in the biosynthesis of functional microtubules. This process involves several chaperones known as Tubulin folding cofactors A (TBCA), B (TBCB), C (TBCC), D (TBCD), and E (TBCE), which act on folding intermediates downstream of the cytosolic chaperone TCP. TBCB, a 244 amino acid cytoplasmic protein, contains a CAP-Gly domain and is ubiquitously expressed. It participates in regulating tubulin heterodimer dissociation and functions as a negative regulator of axonal growth.
Description
Recombinant TBCB Human, produced in E. coli, is a single polypeptide chain comprising 268 amino acids (1-244) with a molecular weight of 29.9 kDa. It includes a 24 amino acid His-tag fused at the N-terminus and is purified using proprietary chromatographic techniques.
Physical Appearance
Clear, colorless solution, sterile-filtered.
Formulation
The TBCB solution (0.5mg/ml) is supplied in 20mM Tris-HCl buffer (pH 8.0), 100mM NaCl, and 20% glycerol.
Stability
For short-term storage (2-4 weeks), store at 4°C. For extended periods, store frozen at -20°C. Adding a carrier protein (0.1% HSA or BSA) is recommended for long-term storage. Avoid repeated freeze-thaw cycles.
Purity
Purity is determined to be greater than 90% by SDS-PAGE analysis.
Synonyms
Tubulin folding cofactor B, Cytoskeleton-associated protein CKAPI, cytoskeleton associated protein 1, CKAP1, CG22, Tubulin-specific chaperone B.
Source
E.coli.
Amino Acid Sequence
MGSSHHHHHH SSGLVPRGSH MGSHMEVTGV SAPTVTVFIS SSLNTFRSEK RYSRSLTIAE FKCKLELLVG SPASCMELEL YGVDDKFYSK LDQEDALLGS YPVDDGCRIH VIDHSGARLG EYEDVSRVEK YTISQEAYDQ RQDTVRSFLK RSKLGRYNEE ERAQQEAEAA QRLAEEKAQA SSIPVGSRCE VRAAGQSPRR GTVMYVGLTD FKPGYWIGVR YDEPLGKNDG SVNGKRYFEC QAKYGAFVKP AVVTVGDFPE EDYGLDEI

Q&A

What is TBCB and what is its role in human cellular function?

TBCB is a microtubule-associated protein belonging to the Tubulin Cofactor (TBC) family. It plays a crucial role in the proper folding and assembly of tubulin, which is essential for microtubule formation and function in human cells. Methodologically, researchers identify TBCB function through protein interaction studies, immunofluorescence microscopy to visualize its cellular localization, and genetic knockdown experiments to observe phenotypic changes. The protein's primary function involves chaperoning alpha-tubulin in the tubulin folding pathway, ensuring proper cytoskeletal organization necessary for cell division, intracellular transport, and maintaining cell shape .

How is TBCB expression measured in human tissue samples?

TBCB expression in human tissue samples is primarily measured through several complementary techniques. Quantitative reverse transcription PCR (RT-qPCR) is commonly employed to determine mRNA levels, as demonstrated in the AML studies where bone marrow mononuclear cells from patients and healthy donors were compared. RNA sequencing (RNA-seq) provides a more comprehensive transcriptome analysis, allowing researchers to analyze expression patterns across different sample types. Additionally, protein expression can be evaluated through Western blotting and immunohistochemistry to visualize protein levels and localization in tissues. For population-level analysis, researchers frequently leverage public databases such as TCGA-LAML and GEO microarray datasets (like GSE9476 and GSE13159) to compare expression between disease states and normal conditions .

What experimental controls are necessary when studying TBCB expression in human samples?

When designing experiments to study TBCB expression in human samples, several critical controls must be implemented. First, tissue-appropriate normal controls must be included—as seen in AML studies where both healthy donor bone marrow and cord blood CD34+ cells served as controls for comparison with AML patient samples. Second, multiple independent cohorts should be analyzed to validate findings, following the approach where results from TCGA-LAML database were confirmed in separate GEO microarray datasets (GSE9476 and GSE13159). Third, technical controls including housekeeping genes for RT-qPCR normalization ensure accurate quantification of expression differences. Finally, statistical validation through techniques like ROC curve analysis (which yielded an AUC value of 0.731 for TBCB as a discriminator between AML and normal samples) helps establish the significance of observed differences .

How does TBCB expression vary across different human tissues and cell types?

TBCB expression demonstrates significant variability across human tissues and cell types, with particularly notable differences between normal and malignant tissues. Pan-cancer analyses reveal elevated TBCB expression in most tumor types compared to matched normal tissues, with AML showing distinctly higher expression than normal hematopoietic cells. Within the hematopoietic system, AML cell lines exhibit significantly higher TBCB transcription levels compared to cord blood CD34+ cells, suggesting lineage and differentiation-dependent expression patterns. To properly characterize these variations, researchers employ multi-cohort analysis across different tissue repositories, single-cell RNA sequencing to identify cell type-specific expression patterns, and comprehensive tissue microarrays for protein-level validation. The observed tissue specificity suggests potential cell type-dependent functions that may be particularly relevant in rapidly dividing or metabolically active cells .

What mechanisms underlie the correlation between TBCB expression and clinical outcomes in AML patients?

The correlation between high TBCB expression and poor AML prognosis appears to involve multiple complex mechanisms. At the cellular level, experimental evidence indicates that TBCB downregulation suppresses AML cell proliferation by enhancing apoptosis, suggesting direct effects on cell survival pathways. At the molecular level, Gene Ontology (GO) and Gene Set Enrichment Analysis (GSEA) reveal that immune-related signaling pathways are enriched in patients with high TBCB expression. Construction of protein-protein interaction networks identified six hub genes—all immune-related molecules—positively correlated with TBCB expression. Furthermore, the tumor microenvironment in high-TBCB AML patients shows distinct immune infiltration patterns, particularly by NK cells, especially CD56bright NK cells. Importantly, transcriptional levels of NK cell inhibitory receptors and their ligands positively correlate with TBCB, potentially explaining the immunosuppressive environment that contributes to poorer outcomes. These findings were established through multivariate regression analysis demonstrating TBCB as an independent poor prognostic factor, alongside detailed immune infiltration analyses using the ssGSEA algorithm implemented in the GSVA package .

What statistical approaches are most appropriate for analyzing TBCB expression data in relation to patient survival?

When analyzing the relationship between TBCB expression and patient survival, researchers should implement a multi-layered statistical approach. Initially, stratification of patients into high and low TBCB expression groups based on median expression values provides a foundation for comparative analyses. For survival analysis, both Kaplan-Meier curves with log-rank tests and Cox proportional hazards modeling are essential, with the latter allowing adjustment for confounding variables. In the AML studies, univariate and multivariate regression analyses were crucial in establishing TBCB expression as an independent prognostic factor. The calculation of hazard ratios (HR) with 95% confidence intervals (CI) provides quantifiable measures of risk associated with TBCB expression levels. Researchers should also employ ROC curve analysis to assess the discriminatory power of TBCB expression (yielding an AUC of 0.731 in AML studies). For more complex analyses, machine learning approaches including random forest algorithms and support vector machines may enhance predictive modeling, particularly when integrating TBCB with other biomarkers. Statistical packages commonly utilized include pROC (v1.18.0) for ROC analysis and visualization through ggplot2 (v3.3.6) .

How should researchers design experiments to investigate the causative relationship between TBCB expression and disease progression?

Establishing a causative relationship between TBCB expression and disease progression requires a comprehensive experimental design approach. The foundation should be a pre-post randomized group design as described in experimental design literature, with appropriate controls to minimize confounding variables. For in vitro studies, CRISPR-Cas9 gene editing to create TBCB knockout or knockdown models in relevant cell lines (such as AML cell lines) allows for direct assessment of TBCB's functional impact. These should be complemented with overexpression models to demonstrate dose-dependent effects. Phenotypic assays measuring proliferation, apoptosis, cell cycle progression, and migration provide functional readouts. For in vivo validation, xenograft models with modulated TBCB expression can demonstrate effects on tumor growth and metastasis. Molecular mechanisms should be explored through RNA-seq and proteomics to identify downstream effectors and signaling pathways. Additionally, patient-derived xenografts with varying TBCB expression levels offer clinically relevant models. Throughout these experiments, proper randomization (R--GP--O--T--O design), blinding of investigators during assessment, and rigorous statistical analysis are essential to establish causative relationships rather than mere associations .

What are the most effective bioinformatic pipelines for identifying TBCB-associated gene networks and pathways?

Effective bioinformatic analysis of TBCB-associated networks requires a multi-step pipeline incorporating various computational tools. The foundation begins with differential expression analysis between high and low TBCB expression groups using packages like limma or DESeq2. Following identification of differentially expressed genes (DEGs), functional enrichment analysis through GO and GSEA illuminates biological processes, molecular functions, and cellular components associated with TBCB expression patterns. For network construction, protein-protein interaction networks based on these DEGs can be visualized using Cytoscape (v3.9.1) with topological algorithms—including MCC, MNC, and EPC—identifying hub genes within the network. AML studies successfully employed this approach to identify six immune-related hub genes positively correlated with TBCB. Correlation analysis between TBCB and identified hub genes should be performed using Spearman correlation and visualized through packages such as ggplot2 (v3.3.6). For immune-related analyses, algorithms like ssGSEA within the GSVA package (v1.46.0) can estimate immune cell infiltration patterns. Advanced approaches may include weighted gene co-expression network analysis (WGCNA) to identify modules of co-expressed genes and causal network inference using Bayesian approaches to predict directional relationships between TBCB and other genes .

How can researchers integrate TBCB expression data with immune infiltration profiles to better understand disease mechanisms?

Integration of TBCB expression data with immune infiltration profiles requires sophisticated computational and experimental approaches. The computational foundation involves utilizing algorithms like single-sample Gene Set Enrichment Analysis (ssGSEA) implemented through the GSVA package (v1.46.0) to quantify the presence of specific immune cell populations based on characteristic gene signatures. In AML research, this approach revealed that high TBCB expression correlates with increased NK cell infiltration, particularly CD56bright NK cells. To validate computational findings, flow cytometry and mass cytometry (CyTOF) analyses of patient samples stratified by TBCB expression can provide direct quantification of immune cell subsets. Spatial transcriptomics and multiplex immunohistochemistry offer additional insights by preserving spatial relationships between TBCB-expressing cells and immune infiltrates. Mechanistic connections can be explored through co-culture experiments between TBCB-manipulated cells and immune cells, measuring functional outcomes such as cytokine production, cytotoxicity, and immune checkpoint expression. Correlation analyses between TBCB and immune checkpoint molecules (as performed in AML studies) help identify potential therapeutic targets. This integrated approach has revealed that transcriptional levels of NK cell inhibitory receptors and their ligands positively correlate with TBCB expression, providing a potential explanation for the poor prognosis associated with high TBCB expression despite increased NK cell infiltration .

How can TBCB expression be utilized as a prognostic biomarker in clinical settings?

Implementation of TBCB as a prognostic biomarker in clinical settings requires standardized quantification methods and validated clinical cut-off values. RT-qPCR provides a practical and affordable option for clinical laboratories, while next-generation sequencing offers more comprehensive expression profiling. For clinical validation, multi-institutional cohort studies with diverse patient populations are necessary to establish reliable cut-off values that distinguish between favorable and unfavorable prognosis groups. In AML, TBCB expression has been linked to specific clinical features including increased white blood cell counts (p < 0.01), augmented proportions of blasts in peripheral blood (p < 0.05) and bone marrow (p < 0.01), and FLT3 positive mutation (p < 0.01). Integration of TBCB expression with existing prognostic factors—such as cytogenetic risk categories and molecular mutations—can enhance risk stratification models. For implementation in routine clinical care, development of Clinical Laboratory Improvement Amendments (CLIA)-certified assays with quality control measures is essential. Once established, TBCB expression levels could guide treatment intensity decisions, identify candidates for experimental therapies, and help monitor disease progression or treatment response .

What methodological approaches can identify potential therapeutic targets based on TBCB-associated pathways?

Identifying therapeutic targets within TBCB-associated pathways requires integrated approaches combining computational prediction with experimental validation. Initial target discovery can leverage network pharmacology techniques to identify druggable nodes within TBCB-associated protein-protein interaction networks. The six immune-related hub genes identified in AML studies provide a starting point for exploration. High-throughput drug screening using cell lines with varying TBCB expression levels can identify compounds showing differential efficacy. CRISPR-Cas9 screens targeting genes within TBCB-associated pathways can reveal synthetic lethalities that could be therapeutically exploited. For immune-related targets, the observed correlation between TBCB expression and NK cell inhibitory receptors suggests potential for immunotherapeutic approaches. Validation should include in vitro functional assays measuring proliferation, apoptosis, and cell cycle effects, followed by in vivo studies using appropriate animal models. Computational drug repurposing approaches can identify existing compounds that may modulate TBCB-associated pathways. The prediction of drug sensitivity based on expression profiles, as mentioned in the AML studies, provides another avenue for identifying patients most likely to benefit from specific therapeutic approaches .

What single-cell methodologies can advance our understanding of TBCB expression heterogeneity in human tissues?

Single-cell methodologies offer revolutionary approaches to understanding TBCB expression heterogeneity across different cell populations within human tissues. Single-cell RNA sequencing (scRNA-seq) provides high-resolution transcriptomic profiles of individual cells, enabling identification of distinct cell populations with varying TBCB expression patterns. For protein-level analysis, mass cytometry (CyTOF) or single-cell proteomics through technologies like CITE-seq combine antibody-based detection with transcriptomic profiling to correlate TBCB protein levels with other cellular markers. Spatial transcriptomics methods including Visium, MERFISH, or Slide-seq maintain tissue architecture information while providing expression data, revealing spatial relationships between TBCB-expressing cells and their microenvironment. For functional heterogeneity assessment, single-cell CRISPR screens can systematically perturb TBCB and other genes to assess cell type-specific dependencies. Computational integration of these multi-omic data requires specialized algorithms such as Seurat, Scanpy, or Monocle for dimension reduction, clustering, trajectory inference, and integration of different data modalities. These approaches could reveal previously unrecognized cell-type specific roles of TBCB in normal development and disease processes, particularly in complex tissues where cellular heterogeneity may mask important biological signals in bulk analysis .

How can researchers address data contradictions when findings on TBCB function differ between experimental models?

Addressing contradictions in TBCB functional studies across different experimental models requires systematic investigation of context-dependent factors. Researchers should first conduct detailed comparative analyses to identify specific variables that might explain divergent results, including cell type, disease context, experimental conditions, and analytical methods. Cross-validation using multiple methodological approaches—such as genetic knockdown, CRISPR knockout, and overexpression—in the same cellular context can determine whether contradictions arise from methodological differences or genuine biological variability. Meta-analysis of published TBCB studies, following established systematic review protocols, helps identify patterns in contradictory findings and their potential sources. For mechanistic understanding, investigation of tissue-specific protein interaction partners through techniques like BioID or proximity labeling may reveal context-dependent functional networks. Species-specific differences should be explored through evolutionary analysis and comparative studies in orthologous models. When contradictions persist, development of unified mathematical models incorporating context-dependent variables may reconcile apparently conflicting observations into a coherent framework. Throughout this process, transparent reporting of negative results and contradictory findings is essential for advancing the field. The observed differential effects of TBCB across various cancer types highlight the importance of context-specific investigation rather than assuming universal functions .

How does TBCB research in humans connect with broader cancer biology and potential therapeutic innovations?

TBCB research intersects with multiple fundamental aspects of cancer biology, positioning it as a potentially significant contributor to therapeutic innovation. As a microtubule-associated protein, TBCB connects with cytoskeletal dynamics that influence cell division, migration, and metastasis—core hallmarks of cancer. The observed correlation between high TBCB expression and poor prognosis in AML suggests potential roles in therapy resistance and disease persistence. The immune-related pathways enriched in high-TBCB AML patients, particularly involving NK cell inhibitory receptors, connect TBCB biology with tumor immune evasion mechanisms. This creates potential bridges to immunotherapy approaches targeting these inhibitory pathways. From a methodological perspective, the multi-omics approaches used in TBCB research exemplify modern cancer research strategies combining transcriptomics, proteomics, and functional genomics. The protein-protein interaction networks identifying six immune-related hub genes as TBCB interaction partners highlight potential for developing combination therapies targeting multiple nodes in these networks. As targeted therapies and precision oncology continue to evolve, understanding the mechanistic contributions of TBCB to disease progression provides foundations for rational drug design and biomarker-guided treatment selection. Future integration of TBCB with other prognostic markers could enhance risk stratification models and treatment algorithms across multiple cancer types .

Product Science Overview

Function and Mechanism

TBCB is involved in the chaperonin-mediated protein folding pathway. It binds to alpha-tubulin folding intermediates after their interaction with the cytosolic chaperonin complex, leading to the formation of properly folded tubulin heterodimers . This process is essential for maintaining microtubule dynamics and stability.

In humans, the CCT (Chaperonin Containing TCP-1) complex facilitates the folding of quasi-native tubulin by alternately opening and closing two folding chambers . Along with other tubulin folding cofactors (TFCs), TBCB assists in the folding and dimerization of newly synthesized labile alpha- and beta-tubulin monomers .

Biological Importance

TBCB is predicted to be involved in cell differentiation and nervous system development . It may also function as a negative regulator of axonal growth, which is crucial for the proper development and functioning of the nervous system .

Associated Diseases

Mutations or dysregulation of TBCB have been associated with certain diseases, including Primary Ciliary Dyskinesia and Acrorenal Syndrome . These conditions highlight the importance of TBCB in maintaining cellular and physiological homeostasis.

Research and Applications

Research on TBCB has provided insights into its role in microtubule dynamics and its potential implications in various diseases. Understanding the function and regulation of TBCB can lead to the development of therapeutic strategies for conditions associated with microtubule dysfunction.

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