Recombinant UPF0392 protein C35A5.5 (C35A5.5)

Basic Questions About UPF0392 Protein C35A5.5 Structure

Q: What is UPF0392 protein C35A5.5 and what organism does it originate from?

A: UPF0392 protein C35A5.5 is a full-length protein (520 amino acids) derived from the nematode Caenorhabditis elegans. The protein is designated by the UniProt accession number Q18473 and is encoded by the C35A5.5 open reading frame (ORF) . The UPF designation (UP stands for "uncharacterized protein family") indicates that while the protein has been identified and sequenced, its precise biological function remains to be fully characterized within the C. elegans proteome.

Q: Are there any predicted functional domains or motifs in UPF0392 protein C35A5.5 that suggest its biological role?

A: While the UPF0392 designation indicates that this protein belongs to an uncharacterized protein family, sequence analysis can provide insights into potential functions. Researchers should perform computational analyses including transmembrane domain prediction, signal peptide identification, and motif scanning. Based on the amino acid sequence, hydrophobic regions near the N-terminus (positions 19-39) suggest a possible transmembrane segment, which aligns with its classification as a potential transmembrane protein in some databases . Additionally, investigating whether C35A5.5 shares homology with other UPF proteins involved in nonsense-mediated mRNA decay pathways would be valuable, as some UPF proteins function in RNA quality control mechanisms . Experimental approaches such as yeast two-hybrid screens or co-immunoprecipitation studies can help identify binding partners and potential involvement in cellular pathways.

Q: How does UPF0392 protein C35A5.5 relate to other UPF proteins in the nonsense-mediated mRNA decay pathway?

A: While UPF0392 protein C35A5.5 shares the UPF designation with factors involved in nonsense-mediated mRNA decay (NMD), the relationship requires careful investigation. NMD is a quality control mechanism that degrades mRNAs containing premature termination codons. In humans, proteins like UPF1, UPF2, and UPF3 form part of the SURF complex (SMG1-UPF1-eRF1-eRF3) that initiates NMD . Experimental approaches to determine if C35A5.5 participates in similar pathways in C. elegans would include:

• RNA interference (RNAi) knockdown of C35A5.5 followed by transcriptome analysis to identify accumulated mRNAs

• Co-immunoprecipitation experiments to test interaction with known C. elegans NMD factors

• Microscopy studies using fluorescently tagged proteins to determine subcellular localization

The observation that human UPF2 interacts with eRF3 in the SURF complex suggests potential parallels worth investigating in the C. elegans system .

Basic Questions About Recombinant Production

Q: What expression systems are used to produce recombinant UPF0392 protein C35A5.5?

A: Recombinant UPF0392 protein C35A5.5 is commonly produced using Escherichia coli expression systems, as indicated in the commercial product information . E. coli offers several advantages for recombinant protein production including rapid growth, high protein yields, and well-established protocols. The methodology typically involves cloning the C35A5.5 coding sequence into an appropriate expression vector, transformation into a suitable E. coli strain (commonly BL21(DE3) or its derivatives), and induction of protein expression using IPTG or auto-induction media. For optimal expression, codon optimization may be necessary to account for differences between C. elegans and E. coli codon usage patterns. Additionally, fusion tags such as His-tag, GST, or MBP are often incorporated to facilitate purification, though the specific tag type may vary depending on the production process .

Q: What are the recommended storage conditions for recombinant UPF0392 protein C35A5.5?

A: Based on product information, recombinant UPF0392 protein C35A5.5 should be stored in a Tris-based buffer with 50% glycerol at -20°C for regular storage or at -80°C for extended storage periods . Working aliquots can be maintained at 4°C for up to one week. Repeated freeze-thaw cycles should be avoided as they can lead to protein degradation and loss of activity. When preparing aliquots, researchers should use sterile techniques and consider including protease inhibitors to prevent degradation. The high glycerol content (50%) serves as a cryoprotectant, preventing damage to the protein structure during freezing. For experiments requiring lower glycerol concentrations, dialysis or buffer exchange using centrifugal concentrators may be necessary prior to use.

Advanced Questions About Expression Optimization

Q: How can I optimize expression conditions for recombinant UPF0392 protein C35A5.5 to improve yield and solubility?

A: Optimizing expression of recombinant UPF0392 protein C35A5.5 requires systematic evaluation of multiple parameters. A Design of Experiments (DoE) approach is recommended to efficiently identify optimal conditions while minimizing experimental runs . Key factors to consider include:

• Expression temperature (15-37°C): Lower temperatures often improve protein folding and solubility

• Induction time points and duration (3-24 hours)

• Inducer concentration (0.1-1 mM IPTG)

• Media composition (standard LB vs. enriched media like TB or auto-induction)

• Host strain selection (BL21(DE3), C41/C43, Rosetta, SHuffle)

• Co-expression with chaperones to assist proper folding

A fractional factorial design can help screen these factors, followed by response surface methodology to fine-tune the most influential parameters. For example, a 2³ factorial design testing temperature (18°C vs. 30°C), IPTG concentration (0.1 mM vs. 0.5 mM), and induction time (4h vs. 16h) would require 8 experimental runs plus controls. Analysis of variance (ANOVA) can then identify significant factors and interactions affecting yield and solubility. Solubility can be assessed through SDS-PAGE analysis of soluble and insoluble fractions after cell lysis.

If inclusion body formation remains problematic, solubilization strategies using mild detergents or fusion partners like SUMO or MBP should be explored.

Q: What purification strategy is recommended for obtaining high-purity recombinant UPF0392 protein C35A5.5?

A: A multi-step purification strategy is recommended to achieve high purity recombinant UPF0392 protein C35A5.5 suitable for structural and functional studies. The approach should be tailored based on the tag system used during expression:

• Initial capture: Affinity chromatography

  • For His-tagged protein: Immobilized metal affinity chromatography (IMAC) using Ni-NTA or Co-NTA resins

  • For GST-tagged protein: Glutathione sepharose

  • Buffer conditions: 50 mM Tris-HCl pH 8.0, 300 mM NaCl, with increasing imidazole concentrations for elution in IMAC

• Intermediate purification: Ion exchange chromatography

  • Based on the theoretical pI of UPF0392 protein C35A5.5, select appropriate resin

  • Buffer optimization using salt gradient elution

• Polishing step: Size exclusion chromatography

  • Superdex 200 or similar column to separate monomeric protein from aggregates

  • Buffer composition: 20 mM Tris-HCl pH 7.5, 150 mM NaCl, 5% glycerol

• Tag removal (if necessary):

  • Specific protease digestion (TEV, PreScission, or thrombin depending on construct)

  • Reverse affinity chromatography to remove cleaved tag and protease

Purity should be assessed at each step using SDS-PAGE and Western blotting. For sensitive applications like crystallography, mass spectrometry can verify protein identity and purity. Final protein preparations should undergo activity/functionality testing appropriate to the experimental goals.

Basic Questions About Functional Characterization

Q: What experimental approaches can I use to investigate the function of UPF0392 protein C35A5.5?

A: Several complementary experimental approaches can help elucidate the function of UPF0392 protein C35A5.5:

• In vivo knockdown/knockout studies:

  • RNAi in C. elegans to identify phenotypic changes

  • CRISPR/Cas9 gene editing to generate null mutants

  • Analysis of resulting phenotypes in development, fertility, lifespan

• Protein-protein interaction studies:

  • Yeast two-hybrid screening

  • Co-immunoprecipitation followed by mass spectrometry

  • Proximity labeling approaches (BioID, APEX)

  • If related to NMD, test interactions with known components of this pathway

• Subcellular localization:

  • Immunofluorescence with specific antibodies

  • Expression of fluorescent protein fusions

  • Subcellular fractionation followed by Western blotting

• Biochemical activity assays:

  • ATPase/GTPase activity tests

  • Nucleic acid binding assays

  • Enzymatic function screens

These approaches should be combined with bioinformatic analyses including structural predictions, sequence conservation studies, and comparison to characterized proteins in other organisms.

Q: How can I verify the identity and quality of commercially sourced recombinant UPF0392 protein C35A5.5?

A: Verification of recombinant UPF0392 protein C35A5.5 identity and quality should include:

• SDS-PAGE analysis: To confirm molecular weight (~57 kDa for the native protein, plus any fusion tags)

• Western blotting: Using either tag-specific antibodies or custom antibodies against C35A5.5

• Mass spectrometry:

  • Peptide mass fingerprinting

  • Intact mass determination to verify full-length protein

• N-terminal sequencing: To confirm the first 5-10 amino acids match the expected sequence

• Functional testing: Develop assays based on predicted functions or interactions

• Circular dichroism: To verify proper secondary structure formation

When working with a new batch, these quality control steps help ensure experimental reproducibility. Researchers should also request the certificate of analysis from the supplier, which typically includes purity assessment and batch-specific information.

Advanced Questions About Research Applications

Q: What role might UPF0392 protein C35A5.5 play in nonsense-mediated mRNA decay based on its UPF designation, and how can this be experimentally verified?

A: The UPF designation suggests a potential role in nonsense-mediated mRNA decay (NMD), though this requires experimental validation. To investigate this possibility, a comprehensive experimental approach would include:

• Sequence analysis:

  • Compare UPF0392 protein C35A5.5 with characterized UPF proteins (UPF1, UPF2, UPF3)

  • Identify conserved domains or motifs involved in NMD

• Interaction studies with core NMD factors:

  • Co-immunoprecipitation with C. elegans SMG proteins and eRF1/eRF3

  • In vitro binding assays with purified components

  • Microscopy to detect co-localization with P-bodies or other RNA processing sites

• Functional NMD assays:

  • Measure decay rates of NMD reporter mRNAs in wild-type vs. C35A5.5 knockdown worms

  • RNA-seq to identify transcripts affected by C35A5.5 depletion

  • Polysome profiling to assess impact on translation

• Structure-function analysis:

  • Generate deletion mutants to identify functional domains

  • Test complementation of phenotypes with specific domains

Based on knowledge of human UPF proteins, where UPF2 interacts with eRF3 during NMD initiation in the SURF complex , particular attention should be paid to potential interactions between C35A5.5 and the C. elegans homologs of release factors. If C35A5.5 is involved in NMD, mutations would likely lead to accumulation of transcripts that normally undergo NMD-mediated degradation.

Q: How can I design appropriate ELISA protocols for detecting and quantifying UPF0392 protein C35A5.5 in complex biological samples?

A: Designing an effective ELISA for UPF0392 protein C35A5.5 requires careful consideration of antibody selection, protocol optimization, and validation steps:

• Antibody development and selection:

  • Generate monoconal antibodies against purified recombinant C35A5.5

  • Select epitopes that are accessible and unique to avoid cross-reactivity

  • Validate antibody specificity using Western blotting against C. elegans lysates

• ELISA format selection:

  • Sandwich ELISA: Using two antibodies recognizing different epitopes

  • Competitive ELISA: For smaller samples or when only one antibody is available

• Protocol optimization:

  Parameter	Recommended Range	Optimization Method
  Coating antibody	1-10 μg/mL	Checkerboard titration
  Blocking buffer	BSA (1-5%) or casein	Test different blockers for lowest background
  Sample dilution	1:2 to 1:100	Serial dilutions to establish linearity
  Detection antibody	0.1-2 μg/mL	Titration against standard curve
  Incubation time	1-16 hours	Time course experiments
  Incubation temperature	4°C, RT, 37°C	Compare signal-to-noise ratios

• Standard curve preparation:

  • Use purified recombinant UPF0392 protein C35A5.5

  • Prepare in the same matrix as samples (e.g., C. elegans lysate)

  • Include range of 0-1000 ng/mL with 7-8 dilution points

• Validation experiments:

  • Spike-and-recovery tests to assess matrix effects

  • Precision testing (intra- and inter-assay CV <15%)

  • Limit of detection/quantification determination

  • Specificity testing against lysates from C35A5.5 knockout worms

The optimized ELISA can then be used to quantify C35A5.5 in various developmental stages, tissues, or experimental conditions to provide insights into its expression patterns and regulation.

Basic Questions About Structural Analysis

Q: What approaches can I use to analyze the structure of recombinant UPF0392 protein C35A5.5?

A: Multiple complementary techniques can be employed to analyze the structure of recombinant UPF0392 protein C35A5.5:

For crystallography studies, initial crystallization screens should test hundreds of conditions, followed by optimization of promising hits. For all structural studies, a highly pure (>95%), homogeneous protein sample is essential, and testing different buffer conditions may be necessary to identify the optimal stability conditions.

Q: How do I determine if recombinant UPF0392 protein C35A5.5 forms oligomers, and what is the significance of its oligomeric state?

A: Determining the oligomeric state of UPF0392 protein C35A5.5 involves several complementary techniques:

• Size exclusion chromatography (SEC):

  • Compare elution volume to molecular weight standards

  • SEC coupled with multi-angle light scattering (SEC-MALS) for absolute molecular weight determination

• Analytical ultracentrifugation (AUC):

  • Sedimentation velocity experiments to determine distribution of species

  • Sedimentation equilibrium for precise molecular weight determination

• Native PAGE or blue native PAGE:

  • Compares migration with standards under non-denaturing conditions

  • Western blotting can confirm identity of bands

• Crosslinking studies:

  • Chemical crosslinkers (BS3, glutaraldehyde) followed by SDS-PAGE

  • Mass spectrometry to identify crosslinked residues

• Microscopy techniques:

  • Negative stain electron microscopy for particle visualization

  • Atomic force microscopy for size distribution

The oligomeric state can significantly impact function, as many UPF proteins form functional complexes. For example, if UPF0392 protein C35A5.5 participates in processes similar to human UPF proteins in nonsense-mediated mRNA decay, its ability to form protein-protein interactions would be crucial for its function . Determining whether oligomerization is concentration-dependent and identifying conditions that affect assembly/disassembly can provide insights into biological regulation mechanisms.

Advanced Questions About Functional Domains

Q: How can I identify and characterize functional domains within UPF0392 protein C35A5.5 and determine their roles in protein activity?

A: A comprehensive approach to identify and characterize functional domains within UPF0392 protein C35A5.5 involves:

• Computational domain prediction:

  • Sequence analysis using tools like SMART, Pfam, InterPro

  • Secondary structure prediction (PSIPRED, JPred)

  • Disorder prediction (PONDR, IUPred)

  • Homology detection using HHpred or PHYRE2

• Experimental domain mapping:

  • Limited proteolysis to identify stable domains

  • Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to identify structured regions

  • Expression of truncated constructs to test domain boundaries

  • Thermal shift assays to test domain stability

• Structure-function analysis:

  • Generate targeted point mutations in conserved residues

  • Create domain deletion mutants

  • Domain swapping with homologous proteins

• Functional assays for each domain:

  • Protein-protein interaction mapping for each domain

  • RNA binding assays if relevant

  • Enzymatic activity tests appropriate to predicted function

  • In vivo complementation assays with domain mutants

When examining UPF0392 protein C35A5.5, special attention should be paid to potential functional parallels with characterized UPF proteins. For instance, human UPF2 contains three MIF4G domains with distinct functions: MIF4G-3 interacts with UPF3b, while the C-terminal region interacts with eRF3 . Similar domain-specific interactions might exist in C35A5.5 and could be characterized through systematic truncation and binding studies.

Q: What approaches can I use to investigate potential post-translational modifications of UPF0392 protein C35A5.5 and their functional significance?

A: Post-translational modifications (PTMs) can significantly influence protein function, localization, and interactions. To investigate PTMs in UPF0392 protein C35A5.5:

• Computational prediction:

  • Phosphorylation sites (NetPhos, GPS)

  • Glycosylation sites (NetNGlyc, NetOGlyc)

  • SUMOylation, ubiquitination predictions (SUMOplot, UbPred)

  • Other PTM predictions based on sequence motifs

• Mass spectrometry-based detection:

  • Bottom-up proteomics with enrichment strategies for specific PTMs

  • Targeted analysis of predicted modification sites

  • Top-down proteomics to analyze intact protein mass shifts

  • Quantitative PTM analysis comparing different conditions

• Biochemical validation:

  • Phospho-specific antibodies for Western blotting

  • Staining methods (Pro-Q Diamond for phosphorylation, PAS for glycosylation)

  • In vitro modification assays with purified kinases or other enzymes

  • Mobility shift assays (Phos-tag gels for phosphorylation)

• Functional significance testing:

  • Site-directed mutagenesis of modified residues (e.g., S/T to A for phosphorylation)

  • Phosphomimetic mutations (S/T to D/E)

  • Comparing wild-type and mutant protein in functional assays

  • Temporal analysis of modifications during different cellular processes

If UPF0392 protein C35A5.5 functions in pathways similar to NMD, phosphorylation may be particularly relevant, as human UPF1 is regulated by phosphorylation by SMG1 kinase during NMD . Identifying condition-specific modifications (e.g., developmental stage, stress response) can provide insights into the regulation of C35A5.5 function.

Basic Questions About Homology and Conservation

Q: Does UPF0392 protein C35A5.5 have homologs in other species, and what can we learn from evolutionary conservation patterns?

• Sequence homology searches:

  • BLAST against protein databases (nr, SwissProt)

  • Profile-based searches using HMMer or PSI-BLAST

  • Identify both orthologs (same function, different species) and paralogs (related genes within C. elegans)

• Multiple sequence alignment:

  • Align C35A5.5 with identified homologs using MUSCLE, MAFFT, or T-Coffee

  • Identify conserved residues and motifs

  • Generate conservation scores for each position

• Phylogenetic analysis:

  • Construct phylogenetic trees using maximum likelihood or Bayesian methods

  • Determine evolutionary relationships

  • Identify potential gene duplication/loss events

• Functional inference:

  • Examine if homologs have known functions

  • Identify experimentally characterized proteins in model organisms

  • Compare expression patterns across species

While specific information about C35A5.5 homologs is limited in the provided search results, the UPF designation suggests potential functional relationships to nonsense-mediated mRNA decay factors. Examining whether the sequence contains domains similar to characterized UPF proteins like UPF1, UPF2, or UPF3 would be informative . Conservation analysis can highlight functionally important residues that have been maintained through evolutionary pressure.

Q: How can I use knowledge from other UPF family proteins to guide my research on UPF0392 protein C35A5.5?

A: Insights from well-characterized UPF family proteins can inform research directions for UPF0392 protein C35A5.5:

• Domain architecture comparison:

  • Compare with known UPF proteins (UPF1, UPF2, UPF3)

  • Identify similar structural motifs or domains

  • Look for conserved functional regions (e.g., MIF4G domains in UPF2)

• Interaction partner prediction:

  • Test if C35A5.5 interacts with known UPF protein partners

  • Investigate if it binds components of the translation machinery

  • Examine potential interactions with RNA or ribosomes

• Functional assay design:

  • Adapt assays used to characterize other UPF proteins

  • Test for involvement in RNA quality control processes

  • Examine roles in translation termination

• Phenotypic analysis:

  • Compare phenotypes of C35A5.5 knockdown/knockout with those of other UPF proteins

  • Look for overlapping functions in developmental processes

Human UPF2 contains three MIF4G domains and interacts with UPF3b, UPF1, and eRF3 during nonsense-mediated mRNA decay . If C35A5.5 shares functional similarities, it might participate in protein complexes involved in RNA surveillance. Testing for interactions with C. elegans homologs of these factors could provide functional insights. Additionally, examining whether C35A5.5 associates with ribosomes, as is observed with human UPF proteins, would be informative .

Advanced Questions About Comparative Genomics

Q: How can comparative genomics and systems biology approaches be leveraged to predict the function of UPF0392 protein C35A5.5?

A: Integrating comparative genomics and systems biology provides powerful approaches to predict UPF0392 protein C35A5.5 function:

• Genomic context analysis:

  • Examine neighboring genes in C. elegans genome

  • Compare gene clusters across species (synteny analysis)

  • Identify operons or co-regulated gene groups

• Co-expression network analysis:

  • Analyze transcriptome data to identify genes with similar expression patterns

  • Construct co-expression networks from multiple conditions

  • Identify functional modules containing C35A5.5

• Protein-protein interaction prediction:

  • Integrate interactome data from model organisms

  • Use orthology-based interaction transfer

  • Predict interaction partners based on domain composition

• Phenome analysis:

  • Compare phenotypes from C. elegans RNAi or deletion screens

  • Integrate phenotypic data across model organisms

  • Use phenologs (phenotypes related by orthology) to predict function

• Metabolic and signaling pathway placement:

  • Map onto known pathways based on interaction predictions

  • Identify potential regulatory relationships

  • Test predictions with targeted experiments

This multi-layered approach can place UPF0392 protein C35A5.5 within a functional context. For example, if C35A5.5 is co-expressed with RNA processing factors or shows similar phenotypes to NMD components when disrupted, this would support a role in RNA metabolism. The STRING database (6239.C35A5.5) provides interaction predictions that could guide experimental validation .

Q: How does recombinant protein technology for UPF0392 protein C35A5.5 differ from approaches used for other challenging C. elegans proteins, and what can we learn from these comparisons?

A: Recombinant protein technology for UPF0392 protein C35A5.5 can be compared with approaches for other challenging C. elegans proteins to identify optimal strategies:

• Expression system selection:

  • E. coli is commonly used for C35A5.5 , but other C. elegans proteins may require:

  • Insect cell systems for complex proteins requiring eukaryotic PTMs

  • Cell-free expression for toxic proteins

  • Yeast systems for membrane proteins

  • Comparative analysis of expression yields and solubility in different systems

• Solubility enhancement strategies:

  • Fusion partners (SUMO, MBP, thioredoxin) effectiveness for different protein classes

  • Detergent screening for membrane or hydrophobic proteins

  • Deletion of problematic regions (signal peptides, transmembrane domains)

  • Co-expression with binding partners or chaperones

• Purification approach optimization:

  • Tag selection based on protein characteristics

  • Buffer composition effects on stability

  • Refolding protocols for inclusion bodies

  • Column selection for different protein properties

• Functional assay development:

  • In vitro reconstitution of biological processes

  • Activity assays appropriate to predicted function

  • Structural analysis approaches

The Design of Experiments (DoE) approach used in recombinant protein production allows systematic optimization of these parameters . Comparing successful strategies across multiple C. elegans proteins can reveal patterns related to protein families, physicochemical properties, or functional classes. These insights can guide the development of optimized protocols for UPF0392 protein C35A5.5 production and functional characterization.