YBR137W Antibody

What is YBR137W and why would researchers need specific antibodies against it?

YBR137W is a gene in Saccharomyces cerevisiae that encodes a protein (Ybr137wp) implicated in the guided entry of tail-anchored (TA) protein (GET) pathway. This pathway facilitates the delivery of tail-anchored membrane proteins to the endoplasmic reticulum. Researchers would need specific antibodies against YBR137W protein to investigate its expression patterns, localization, interactions, and functional role in the GET pathway.

The protein encoded by YBR137W forms a decamer in solution, as confirmed by size exclusion chromatography and analytical ultracentrifugation studies, with a molecular mass of approximately 230-250 kDa . YBR137W is particularly interesting because it associates with the sorting complex of the GET pathway, which includes Sgt2, Get4, and Get5 proteins. Antibodies specific to YBR137W are essential for studying its expression levels during different growth phases, as the protein shows significant upregulation when yeast cells exit the log phase .

What protocols are recommended for Western blotting with YBR137W antibodies?

For effective Western blotting of YBR137W protein, the following methodological approach is recommended based on published research:

• Cell preparation: Harvest approximately 2 ml of yeast cells and measure OD600 to ensure equal loading.

• Cell lysis: Resuspend cells in 0.1 N NaOH and incubate on ice for 15 minutes.

• Sample preparation: Resuspend treated cells in 1× SDS sample buffer and heat at 95°C for 5 minutes.

• Electrophoresis: Separate proteins using Bis-Tris 4-12% acrylamide gels.

• Transfer: Transfer proteins onto a polyvinylidene difluoride (PVDF) membrane.

• Blocking: Block the membrane in phosphate-buffered saline-Tween (PBST) containing 3% bovine serum albumin (BSA).

• Primary antibody incubation: Incubate with rabbit polyclonal antibodies against Ybr137wp at room temperature for 1 hour.

• Secondary antibody incubation: Incubate with appropriate secondary antibodies.

• Detection: Use enhanced chemiluminescence or similar detection method.

When performing Western blotting, it's crucial to include a loading control such as glucose-6-phosphate dehydrogenase (G6PDH), which has been successfully used in published YBR137W research .

How can researchers detect changes in YBR137W expression during different growth phases?

To detect changes in YBR137W expression during different growth phases, researchers should employ a time-course experiment with the following methodological considerations:

• Culture preparation: Establish consistent starter cultures by subculturing yeast daily in fresh YPD medium for 3 days.

• Growth conditions: Subculture in YPD medium and grow to log phase (OD600 of ~0.5-1.0).

• Medium transfer: Wash cells twice with the appropriate medium (YPD or synthetic complete medium) and resuspend in the same medium.

• Time-point collection: Harvest 2 ml of cells at specific time points (e.g., 0, 6, 14, 24 hours).

• Protein extraction: Process samples as described in the Western blotting protocol.

• Quantification: Normalize YBR137W protein levels to a housekeeping protein such as G6PDH.

According to research findings, YBR137W protein expression is minimal during log phase but increases significantly after 14 hours of culture and reaches maximal levels at 24 hours in YPD medium. In synthetic complete (SC) medium, maximal expression occurs earlier, at approximately 14 hours . This expression pattern coincides with the diauxic shift in yeast metabolism, suggesting YBR137W may play a role in adapting to nutrient limitation.

What controls should be included when using YBR137W antibodies in research?

When conducting experiments with YBR137W antibodies, the following controls are essential for ensuring reliable and interpretable results:

• Negative control: Include samples from a ybr137w deletion strain (Δybr137w) to confirm antibody specificity.

• Positive control: Use samples from wild-type strains known to express YBR137W, particularly from post-log phase cultures where expression is highest.

• Loading control: Employ antibodies against housekeeping proteins like G6PDH to normalize protein loading across samples.

• Expression validation: For complementation studies, include samples from Δybr137w strains transformed with a plasmid bearing the YBR137W gene under its endogenous promoter.

• Cross-reactivity control: Test the antibody against purified recombinant YBR137W protein when available.

These controls help address potential issues related to antibody specificity, sample preparation variability, and expression level differences across experimental conditions .

How should experiments be designed to investigate YBR137W interactions with the GET pathway components?

To investigate YBR137W interactions with GET pathway components, a comprehensive experimental approach should include:

• In vitro binding assays:

  • Express and purify recombinant proteins (YBR137W and GET components like Sgt2)

  • Perform size exclusion chromatography (SEC) to analyze complex formation

  • Conduct isothermal titration calorimetry (ITC) to determine binding affinities and stoichiometry

  • Create truncated constructs (e.g., YBR137WΔC lacking the C-terminal domain) to map interaction domains

• Co-immunoprecipitation studies:

  • Use antibodies against YBR137W or GET pathway components

  • Include appropriate controls (IgG control, deletion strains)

  • Perform reciprocal co-IPs to confirm interactions

• Functional studies:

  • Generate single and double deletion strains (e.g., Δybr137w, Δget3, Δybr137w Δget3)

  • Assess phenotypes under different conditions (temperature, nutrient availability)

  • Perform complementation experiments with wild-type and mutant constructs

Research has shown that YBR137W interacts specifically with the tetratricopeptide repeat (TPR) domain of Sgt2 via its C-terminal acidic motif (EEDL). ITC experiments determined a dissociation constant (Kd) of approximately 1.36 ± 0.09 μM for the YBR137W/Sgt2ΔC interaction in buffer containing 20 mM Tris-HCl (pH 8.0) and 100 mM NaCl .

What methodologies are effective for studying YBR137W's role in tail-anchored protein targeting?

To study YBR137W's role in tail-anchored protein targeting, researchers should consider the following methodological approaches:

• Localization studies of TA proteins:

  • Generate strains expressing tagged TA proteins (e.g., Flag-tagged Sec22 or GFP-tagged SCS2)

  • Compare localization patterns in wild-type, Δybr137w, ΔGET component, and double deletion strains

  • Quantify the formation of puncta containing mislocalized TA proteins

  • Perform complementation experiments with YBR137W expression constructs

• Viability assays under stress conditions:

  • Culture cells in different media (YPD, SC, SC with galactose instead of glucose)

  • Assess cell viability through serial dilution spot assays

  • Compare growth at different temperatures (30°C, 40°C)

  • Evaluate growth over extended periods (up to 5 days) to detect late-phase effects

• Biochemical fractionation:

  • Separate cellular components to track the distribution of TA proteins

  • Compare membrane integration efficiency of TA proteins across different genetic backgrounds

How can researchers investigate the structural properties of YBR137W using antibodies?

To investigate the structural properties of YBR137W using antibodies, researchers should implement a multi-method approach:

• Native protein complex detection:

  • Perform blue native PAGE using proteins from yeast crude extracts

  • Western blot with YBR137W antibodies to detect native oligomeric state

  • Compare with purified recombinant YBR137W protein as a reference

• Crosslinking studies:

  • Treat cells or purified protein with chemical crosslinkers of varying lengths

  • Analyze crosslinked products by SDS-PAGE followed by Western blotting with YBR137W antibodies

  • Identify crosslinked partners using mass spectrometry

• Immunoprecipitation for structural studies:

  • Use YBR137W antibodies to pull down native complexes

  • Analyze complex composition by mass spectrometry

  • Perform electron microscopy on immunoprecipitated complexes

Research has confirmed that YBR137W forms a decamer in solution with a molecular mass of approximately 230-250 kDa. This has been verified through multiple methods including size exclusion chromatography (SEC), analytical ultracentrifugation (AUC) with a sedimentation coefficient of 9.2 S, and blue native PAGE analysis of endogenous YBR137W .

What approaches can detect the interaction between YBR137W and Sgt2?

To detect and characterize the interaction between YBR137W and Sgt2, researchers should employ the following methodological approaches:

• In vitro binding assays:

  • Express and purify recombinant proteins (full-length or domains)

  • Perform pull-down assays with tagged proteins

  • Use isothermal titration calorimetry (ITC) to determine binding parameters

  • Conduct size exclusion chromatography (SEC) to assess complex formation

• Mutagenesis studies:

  • Generate truncation constructs (e.g., YBR137WΔC lacking the C-terminal acidic motif)

  • Create point mutations in the interaction interface

  • Assess binding using the methods above

• Co-immunoprecipitation from yeast:

  • Use antibodies against YBR137W or Sgt2

  • Include appropriate controls (IgG control, deletion strains)

  • Confirm specificity with competition experiments

Research has demonstrated that YBR137W interacts with Sgt2 through its C-terminal acidic motif (EEDL). The interaction specifically involves the TPR domain of Sgt2, with a binding affinity (Kd) of approximately 1.36-1.38 μM as determined by ITC. The stoichiometry of approximately 0.99 indicates that one YBR137W decamer can interact with five Sgt2ΔC dimers. Deletion of the C-terminal acidic motif (YBR137WΔC) completely abolishes the interaction with Sgt2 .

How can researchers use YBR137W antibodies to study cellular responses to nutrient limitation?

To study cellular responses to nutrient limitation using YBR137W antibodies, researchers should implement the following methodological approach:

• Time-course expression analysis:

  • Culture yeast in rich medium (YPD) until log phase

  • Transfer to nutrient-limited conditions (e.g., SC medium or SC-D medium with galactose)

  • Collect samples at regular intervals (e.g., 0, 6, 14, 24, 48 hours)

  • Analyze YBR137W expression by Western blotting

  • Correlate expression changes with metabolic shifts (e.g., diauxic shift)

• Co-expression studies:

  • Simultaneously monitor YBR137W and GET pathway components

  • Assess correlation between expression patterns

  • Identify potential co-regulation mechanisms

• Stress response experiments:

  • Expose cells to various stressors (nutrient limitation, temperature, osmotic stress)

  • Compare YBR137W expression across conditions

  • Perform epistasis analysis using deletion strains

Research has shown that YBR137W expression increases significantly as yeast cells exit the log phase, reaching maximal levels at 24 hours in YPD medium and 14 hours in SC medium. This expression pattern coincides with the diauxic shift when glucose is depleted. Furthermore, while deletion of GET pathway components (get3, get5, sgt2) reduces cell viability in SC medium with galactose, additional deletion of ybr137w rescues this phenotype, suggesting YBR137W mediates GET-dependent defects during nutrient limitation .

What methodological approaches help investigate YBR137W's role in modulating GET pathway function?

To investigate YBR137W's role in modulating GET pathway function, researchers should employ these methodological approaches:

• Genetic interaction studies:

  • Generate single and double deletion strains (e.g., Δybr137w, Δget3, Δget5, Δsgt2, and corresponding double deletions)

  • Assess phenotypes under various conditions (temperature, nutrient availability)

  • Perform epistasis analysis to determine genetic relationships

• TA protein localization analysis:

  • Express tagged TA proteins (e.g., Flag-Sec22, GFP-SCS2) in different genetic backgrounds

  • Use fluorescence microscopy to assess localization patterns

  • Quantify puncta formation as an indicator of defective TA protein targeting

  • Perform complementation experiments with YBR137W expression constructs

• Biochemical fractionation:

  • Separate cellular components to analyze TA protein distribution

  • Compare membrane integration efficiency across strains

  • Assess GET component distribution during stress conditions

Research has demonstrated that deletion of YBR137W rescues defects in TA protein targeting observed in GET pathway mutants. Specifically, Δget3 strains show significant formation of Sec22 and SCS2 puncta, while Δget3 Δybr137w double deletion strains exhibit reduced puncta formation. This rescue effect is reversed when YBR137W is reintroduced via a plasmid, confirming YBR137W's role in mediating GET-dependent phenotypes .

How can researchers design experiments to investigate potential post-translational modifications of YBR137W?

To investigate potential post-translational modifications (PTMs) of YBR137W, researchers should implement the following methodological approach:

• Immunoprecipitation and mass spectrometry:

  • Use YBR137W antibodies to immunoprecipitate the protein from yeast lysates

  • Process samples for mass spectrometry analysis

  • Search for PTMs such as phosphorylation, acetylation, or ubiquitination

  • Compare PTM profiles across different growth conditions

• Phosphorylation-specific studies:

  • Treat immunoprecipitated YBR137W with phosphatases

  • Compare mobility shifts on SDS-PAGE before and after treatment

  • Use phosphorylation-specific antibodies if available

  • Perform radiolabeling with 32P to detect phosphorylation directly

• Site-directed mutagenesis:

  • Identify potential modification sites through bioinformatics prediction tools

  • Create point mutations at these sites

  • Assess functional consequences of mutations on:

    • Interaction with Sgt2

    • Decamer formation

    • Rescue of GET pathway defects

While the search results don't specifically mention PTMs of YBR137W, the protein's regulatory role during nutrient limitation suggests potential regulation through modifications. The C-terminal acidic motif (EEDL) critical for interaction with Sgt2 could be a target for regulatory modifications that modulate its function in the GET pathway .

What experimental designs can help determine if YBR137W homologs exist in other organisms?

To investigate whether YBR137W homologs exist in other organisms, researchers should employ the following methodological approaches:

• Bioinformatic analysis:

  • Use sequence-based tools (BLAST, PSI-BLAST) to search for potential homologs

  • Employ structure-based prediction tools when sequence conservation is low

  • Perform motif searches focusing on the C-terminal acidic motif

  • Conduct phylogenetic analysis to trace evolutionary relationships

• Functional complementation:

  • Identify potential homologs in other organisms

  • Express these candidates in Δybr137w yeast

  • Assess rescue of phenotypes associated with YBR137W deletion

  • Focus particularly on GET-dependent defects under nutrient limitation

• Protein interaction studies:

  • Test if potential homologs interact with Sgt2 or its counterparts in other organisms

  • Use co-immunoprecipitation, yeast two-hybrid, or in vitro binding assays

  • Compare binding affinities and interaction domains

Available research indicates that ybr137w is not conserved outside fungi, even though other components of the TA protein targeting pathway, including Sgt2, are universal to all eukaryotes. This suggests YBR137W may represent a fungal-specific adaptation in the GET pathway .

What factors might affect the detection of YBR137W protein in Western blot experiments?

Several factors can affect the detection of YBR137W protein in Western blot experiments:

• Growth phase considerations:

  • YBR137W expression is minimal during log phase but increases significantly after yeast exit this phase

  • Samples collected during log phase may show very low or undetectable levels

  • For optimal detection, collect samples after 14-24 hours of culture when expression peaks

• Lysis method optimization:

  • The structure of YBR137W (a decamer of approximately 230-250 kDa) may require specific lysis conditions

  • Adjust lysis buffers to preserve protein integrity while ensuring efficient extraction

  • Consider native vs. denaturing conditions based on experimental goals

• Antibody-related factors:

  • Ensure antibody specificity by including Δybr137w controls

  • Optimize antibody concentration and incubation conditions

  • Consider using polyclonal antibodies that recognize multiple epitopes

• Media and culture conditions:

  • YBR137W expression patterns differ between rich (YPD) and synthetic (SC) media

  • Expression peaks earlier in SC medium (14h) compared to YPD medium (24h)

  • Carbon source availability significantly impacts expression levels

Research has shown that YBR137W expression is tightly linked to the metabolic state of yeast cells, particularly the diauxic shift when glucose is depleted. This expression pattern must be considered when designing experiments to detect the protein .

How should researchers interpret conflicting results regarding YBR137W's role in different genetic backgrounds?

When encountering conflicting results regarding YBR137W's role in different genetic backgrounds, researchers should consider these methodological approaches for interpretation:

• Strain background effects:

  • Compare the complete genotypes of different strains used

  • Consider laboratory-specific adaptations in commonly used strains

  • Test the phenotype in multiple independent strain backgrounds

  • Ensure proper genotype verification of all strains

• Growth condition variations:

  • Carefully control and report all growth conditions (media composition, temperature, aeration)

  • Consider that YBR137W's function appears particularly relevant under nutrient limitation

  • Replicate experiments using precisely defined synthetic media

  • Test multiple stress conditions to identify specific triggers for YBR137W activity

• Temporal considerations:

  • YBR137W's effects may be growth-phase dependent

  • Perform time-course experiments rather than single time-point measurements

  • Consider both short-term and long-term phenotypes (up to 5 days)

The research demonstrates that YBR137W's role becomes particularly evident under stress conditions. For example, deletion of GET pathway components shows minimal phenotypes at 30°C but significant viability defects at 40°C. Similarly, the rescue effect of YBR137W deletion on GET pathway mutants is more pronounced in SC medium with galactose rather than glucose .

What controls are essential when using YBR137W antibodies to study protein-protein interactions?

When using YBR137W antibodies to study protein-protein interactions, the following controls are essential:

• Antibody specificity controls:

  • Include samples from Δybr137w strains to confirm no cross-reactivity

  • Use purified recombinant YBR137W protein as a positive control

  • Include isotype-matched irrelevant antibodies as negative controls for immunoprecipitation

• Interaction validation controls:

  • Perform reciprocal co-immunoprecipitation (co-IP) using antibodies against interaction partners

  • Include domain deletion constructs (e.g., YBR137WΔC lacking the C-terminal acidic motif)

  • Use competing peptides to confirm specificity of interactions

• Buffer condition controls:

  • Test multiple buffer compositions to ensure optimal detection of true interactions

  • Include detergent controls to distinguish membrane-dependent from direct interactions

  • Verify that immunoprecipitation conditions maintain native protein conformations

• Quantitative controls:

  • Use known quantities of purified proteins to establish standard curves

  • Include internal controls for normalization across experiments

  • Perform binding assays with purified components to confirm direct interactions

Research has demonstrated that YBR137W interacts with Sgt2 through its C-terminal acidic motif, with a binding affinity (Kd) of approximately 1.36-1.38 μM. This interaction is completely abolished when the C-terminal acidic motif is deleted, providing an excellent negative control for interaction studies .

How can researchers address challenges in detecting the oligomeric state of YBR137W?

To address challenges in detecting the oligomeric state of YBR137W, researchers should implement the following methodological approaches:

• Sample preparation optimization:

  • Carefully control cell lysis conditions to preserve native protein complexes

  • Use mild detergents when necessary for membrane-associated fractions

  • Avoid excessive heating or strong reducing agents that might disrupt the decameric structure

  • Consider crosslinking approaches to stabilize complexes prior to analysis

• Multiple detection techniques:

  • Combine complementary approaches such as:

    • Size exclusion chromatography (SEC)

    • Analytical ultracentrifugation (AUC)

    • Blue native PAGE

    • Dynamic light scattering

  • Compare results across methods to build confidence in oligomeric state determination

• Concentration dependence analysis:

  • Test multiple protein concentrations to assess oligomerization equilibrium

  • Determine if the decameric state is concentration-dependent

  • Consider potential concentration differences between in vitro and in vivo conditions

Research has confirmed that YBR137W forms a decamer in solution with a molecular mass of approximately 230-250 kDa. This has been verified through multiple methods including SEC, AUC (with a sedimentation coefficient of 9.2 S), and blue native PAGE analysis of endogenous YBR137W. The consistency across methods suggests that the decameric structure is likely essential for YBR137W function .

What experimental approaches could reveal how YBR137W expression is regulated during stress conditions?

To investigate how YBR137W expression is regulated during stress conditions, researchers should consider these methodological approaches:

• Promoter analysis:

  • Perform chromatin immunoprecipitation (ChIP) to identify transcription factors binding the YBR137W promoter

  • Create reporter constructs with the YBR137W promoter driving fluorescent protein expression

  • Conduct promoter deletion analysis to identify key regulatory elements

  • Compare promoter activity across various stress conditions

• Transcriptional regulation studies:

  • Perform RNA-seq or qRT-PCR to monitor YBR137W mRNA levels under different conditions

  • Screen transcription factor deletion libraries to identify regulators of YBR137W

  • Investigate potential co-regulation with other stress response genes

  • Assess the role of chromatin remodeling in YBR137W regulation

• Post-transcriptional regulation:

  • Analyze mRNA stability under different conditions

  • Investigate potential regulation by RNA-binding proteins

  • Assess the role of non-coding RNAs in modulating YBR137W expression

Research has shown that YBR137W expression increases significantly as yeast cells exit the log phase, coinciding with the diauxic shift when glucose is depleted. This expression pattern suggests regulation linked to nutrient sensing pathways. Further investigation could reveal whether this regulation involves stress-responsive transcription factors or metabolic sensors .

How might advanced structural biology techniques enhance our understanding of YBR137W function?

Advanced structural biology techniques could significantly enhance our understanding of YBR137W function through these methodological approaches:

• High-resolution structural studies:

  • X-ray crystallography to improve upon the current 2.8-Å-resolution crystal structure

  • Cryo-electron microscopy to visualize the full decameric complex

  • Nuclear magnetic resonance (NMR) to analyze dynamics of interaction interfaces

  • Single-particle analysis to determine structural heterogeneity

• Structure-function relationship investigation:

  • Identify critical residues for decamer formation and Sgt2 interaction

  • Design point mutations based on structural information

  • Perform functional complementation with mutant constructs

  • Map interaction surfaces with other potential binding partners

• Conformational dynamics studies:

  • Hydrogen-deuterium exchange mass spectrometry to analyze protein dynamics

  • Förster resonance energy transfer (FRET) to study conformational changes

  • Molecular dynamics simulations to predict structural behavior

The current 2.8-Å-resolution crystal structure has revealed that YBR137W forms a decamer, and its C-terminal acidic motif is critical for interaction with the TPR domain of Sgt2. Advanced structural studies could further elucidate how this decameric structure contributes to YBR137W's function in modulating the GET pathway, particularly under stress conditions .

What approaches could determine if YBR137W interacts with components beyond the known GET pathway?

To investigate potential interactions between YBR137W and components beyond the known GET pathway, researchers should employ these methodological approaches:

• Unbiased interaction screening:

  • Perform immunoprecipitation followed by mass spectrometry (IP-MS)

  • Conduct yeast two-hybrid screens using YBR137W as bait

  • Implement BioID or proximity labeling approaches to identify nearby proteins

  • Use protein microarrays to test for direct interactions with candidate proteins

• Focused candidate testing:

  • Investigate interactions with stress response pathways

  • Test connections to nutrient sensing mechanisms

  • Examine potential links to protein quality control systems

  • Assess overlap with other membrane protein targeting pathways

• Genetic interaction mapping:

  • Perform synthetic genetic array analysis with YBR137W deletion

  • Conduct dosage suppressor screens to identify genetic interactions

  • Use CRISPR-based screens to identify functional relationships

How can quantitative systems biology approaches be applied to understand YBR137W's role in cellular homeostasis?

To apply quantitative systems biology approaches to understand YBR137W's role in cellular homeostasis, researchers should implement the following methodological strategies:

• Integrative omics analysis:

  • Combine transcriptomics, proteomics, and metabolomics data

  • Compare wild-type and Δybr137w strains under various conditions

  • Identify pathways and processes affected by YBR137W deletion

  • Construct network models of YBR137W's functional interactions

• Mathematical modeling:

  • Develop kinetic models of the GET pathway incorporating YBR137W

  • Simulate the effects of varying YBR137W levels on pathway flux

  • Model the dynamic response to nutrient limitation

  • Predict system behavior under novel conditions for experimental validation

• Single-cell analysis:

  • Examine cell-to-cell variability in YBR137W expression

  • Correlate expression with phenotypic outcomes at the single-cell level

  • Investigate potential bet-hedging strategies in stress response

Research has shown that YBR137W expression is induced as yeast exit the log phase and that it affects TA protein delivery and cell viability under stress conditions. A systems biology approach could help quantify these effects and place YBR137W in the broader context of cellular stress response networks. This would be particularly valuable for understanding how YBR137W contributes to cellular homeostasis during the transition from nutrient-rich to nutrient-limited conditions .