| Field | Specification |
|---|---|
| Mfr No | |
| Activity | |
| Alternative Names | Polyprotein P1234; partial; (P1234)(Non-structural polyprotein) |
| Conjugate | |
| Endotoxin Level | |
| Expression System | |
| Form | Liquid or Lyophilized powder |
| Molecular Weight | |
| Product Type | |
| Protein Length | |
| Purity | |
| Reconstitution | |
| Species | |
| Storage | |
| Target | |
| UniProt # |
Overview
Recombinant Semliki forest virus Polyprotein P1234, partial is a recombinant protein reagent derived from Semliki forest virus (SFV) and produced in E.coli. It is commonly used to support Others research by enabling binding assays, assay development and protein–protein interaction studies in controlled in vitro settings.
Key elements and design rationale
- Expressed region: 29-260aa. Region selection can focus on functional domains, improve solubility, or isolate interaction surfaces for targeted studies.
- Expression system: E.coli. Expression host can influence folding and the presence/absence of post-translational modifications.
- Tag / fusion: N-terminal 10xHis-tagged and C-terminal Myc-tagged. Tags can support purification and detection; evaluate potential tag effects when studying sensitive interactions.
- Molecular weight (reported): 33.2 kDa. Apparent size may vary with tags, processing, and gel conditions.
When comparing results across batches or platforms, interpret signals in the context of construct design (region, tags) and expression host, especially for modification-dependent interactions.
Biological background
SFV-PP-P refers to a protein target that is studied across multiple biological contexts; annotations and nomenclature can vary by species and isoform. This product corresponds to the Semliki forest virus (SFV) sequence context, which can be important when comparing homologs or orthologs across model systems. For curated functional annotations, domains, and sequence features, consult primary databases (e.g., UniProt/NCBI) and the recent literature for the specific organism and isoform.
Research relevance and current trends
- Using recombinant proteins to enable quantitative binding measurements and reagent benchmarking.
- Studying domain- and isoform-specific effects in pathway models and interaction networks.
- Developing robust, reproducible assays that connect molecular readouts to cellular phenotypes.
Relevance: [Polyprotein P1234]: Inactive precursor of the viral replicase, which is activated by cleavages carried out by the viral protease nsP2.; [Polyprotein P123]: The early replication complex formed by the polyprotein P123 and nsP4 synthesizes minus-strand RNAs. As soon P123 is cleaved into mature proteins, the plus-strand RNAs synthesis begins.; [Polyprotein P123']: The early replication complex formed by the polyprotein P123' and nsP4 synthesizes minus-strand RNAs (Probable). Polyprotein P123' is a short-lived polyprotein that accumulates during early stage of infection (Probable). As soon P123' is cleaved into mature proteins, the plus-strand RNAs synthesis begins (Probable).; [mRNA-capping enzyme nsP1]: Cytoplasmic capping enzyme that catalyzes two virus-specific reactions: methyltransferase and nsP1 guanylyltransferase. mRNA-capping is necessary since all viral RNAs are synthesized in the cytoplasm, and host capping enzymes are restricted to the nucleus (Probable). The enzymatic reaction involves a covalent link between 7-methyl-GMP and nsP1, whereas eukaryotic capping enzymes form a covalent complex only with GMP (Probable). nsP1 capping consists in the following reactions: GTP is first methylated into 7-methyl-GMP and then is covalently linked to nsP1 to form the m7GMp-nsP1 complex from which 7-methyl-GMP complex is transferred to the mRNA to create the cap structure (Probable). NsP1 is also needed for the initiation of the minus-strand RNAs synthesis. Probably serves as a membrane anchor for the replication complex composed of nsP1-nsP4 (Probable). Palmitoylated nsP1 is remodeling host cell cytoskeleton, and induces filopodium-like structure formation at the surface of the host cell.; [Protease nsP2]: Multifunctional protein whose N-terminus is part of the RNA polymerase complex and displays NTPase, RNA triphosphatase and helicase activities. NTPase and RNA triphosphatase are involved in viral RNA capping and helicase keeps a check on the dsRNA replication intermediates (Probable). The C-terminus harbors a protease that specifically cleaves and releases the mature proteins. Required for the shutoff of minus-strand RNAs synthesis. Specifically inhibits the host IFN response by promoting the nuclear export of host STAT1. Also inhibits host transcription by inducing rapid proteasome-dependent degradation of POLR2A, a catalytic subunit of the RNAPII complex. The resulting inhibition of cellular protein synthesis serves to ensure maximal viral gene expression and to evade host immune response (Probable).; [Non-structural protein 3']: Seems to be essential for minus-strand RNAs and subgenomic 26S mRNAs synthesis. Displays mono-ADP-ribosylhydrolase activity (Probable). ADP-ribosylation is a post-translational modification that controls various processes of the host cell and the virus probably needs to revert it for optimal viral replication (Probable). Binds proteins of FXR family and sequesters them into the viral RNA replication complexes thereby inhibiting the formation of host stress granules on viral mRNAs (Probable). The nsp3'-FXR complexes bind viral RNAs and probably orchestrate the assembly of viral replication complexes, thanks to the ability of FXR family members to self-assemble and bind DNA (Probable).; [Non-structural protein 3]: Seems to be essential for minus-strand RNAs and subgenomic 26S mRNAs synthesis. Displays mono-ADP-ribosylhydrolase activity. ADP-ribosylation is a post-translational modification that controls various processes of the host cell and the virus probably needs to revert it for optimal viral replication. Binds proteins of G3BP family and sequesters them into the viral RNA replication complexes thereby inhibiting the formation of host stress granules on viral mRNAs. The nsp3-G3BP complexes bind viral RNAs and probably orchestrate the assembly of viral replication complexes, thanks to the ability of G3BP family members to self-assemble and bind DNA.; [RNA-directed RNA polymerase nsP4]: RNA dependent RNA polymerase. Replicates genomic and antigenomic RNA by recognizing replications specific signals. The early replication complex formed by the polyprotein P123 and nsP4 synthesizes minus-strand RNAs. The late replication complex composed of fully processed nsP1-nsP4 is responsible for the production of genomic and subgenomic plus-strand RNAs.
Common research applications
- Assay and standard development for immunoassays or binding-based detection methods.
- Protein–protein interaction studies (e.g., receptor–ligand or complex assembly) using purified components.
- Structure–function analysis, including domain mapping or evaluation of sequence variants.
In quantitative assay development, changes in binding or activity readouts are typically interpreted relative to appropriate negative/positive controls and, where possible, orthogonal assay formats that support the same conclusion.
Notes for experimental interpretation
- Recombinant constructs may represent a defined region (domain) rather than the full-length protein; interpret results in the context of the expressed region.
- Tag or fusion elements can aid purification and detection but may influence binding surfaces or oligomerization; consider tag controls when relevant.
- Species and isoform differences can affect interaction partners and post-translational modifications; align experimental controls to the intended biological context.
- E. coli expression can limit eukaryotic post-translational modifications; for modification-dependent biology, interpret results accordingly.
What is protein expression and purification?
Why is there no/low protein expression?
b. Rare codons. You should optimize codons, use strains supplementing rare codons, induce at lower temperature or grow in poor media.
c. Protein toxicity. You should use promoters with tighter regulation or lower plasmid copy number. Use pLysS/pLysE bearing strains in T7-based systems or strains that are better for the expression of toxic proteins. Start induction at high OD and shorten induction time. Add glucose when using expression vectors containing lac-based promoters.
How to avoid inclusion bodies and improve soluble expression?
b. Incorrect disulfide bond formation. You should add fusion partners, including thioredoxin, DsbA, DsbC. Clone in a vector containing secretion signal peptide to cell periplasm. Use gamiB (DE3)strains with oxidative cytoplasmic environment. Lower inducer concentration and induction temperature.
c. Incorrect folding. You should use a fusion partner. Co-express with molecular chaperones. Use strains with cold-adapted chaperones. Supplement media with chemical chaperones and cofactors. Reduce the inducer concentration and add fresh media. Induce for a shorter time at low temperature.
Why is the molecular weight of protein smaller than the predicted?
b. Imbalanced translation process of fusion protein. You should change another fusion tag or move fusion tag to C-terminal. You should induce for a shorter time at low temperature or change to poor media.
c. Protein degradation. You should replace specific protease sites. Use protease deficient strains. Induce at high OD. You should induce for a shorter time at low temperature or use protease inhibitors when breaking cells.
Why is the actual band size different from the predicted?
b. Post-translational cleavage. Many proteins are synthesized as pro-proteins, and then cleaved to give the active form.
c. Splice variants. Alternative splicing may create different sized proteins from the same gene.
d. Relative charge. The composition of amino acids have different relative charge which will affect the electrophoretic mobility.
e. Multimers such as dimerisation of a protein. This is usually prevented in reducing conditions, although strong interactions can result in the appearance of higher bands.
f. Protein structure such as disulfide bond, protein secondary structure or protein 3D structure formation.
g. Hydrophobic proteins, such as transmembrane proteins, may have difficulties in migrating into the gel, and thus resulting in different multi-banded patterns.
How to express a protein with bioactivity? Why is the protein inactive?
a. Low solubility of the protein. You should fuse desired protein to a fusion partners and lower temperature.
b. Lack of essential post translational modification. You should change another expression system.
c. Incomplete folding. You should use a fusion partner and use strains with cold-adapted chaperones. Co-express with molecular chaperones at lower temperature. Monitor disulfide bond formation and allow further folding in vitro.
d. Mutations in cDNA. You should sequence plasmid before and after induction or use a recA− strain to ensure plasmid stability. Transform E. coli before each expression round.
Why are our protein products almost invisible in pipes?
Tips: Before opening the lid, we recommend to centrifuge in a small centrifuge for 20-30 seconds firstly to ensure that the contents are on the bottom of the tube. Our quality control steps ensure that the amount of protein contained in each tube is accurate, although sometimes you can’t see the protein powder, but the protein content in the tube is still very accurate.
How is the protein purified? Is the purity guaranteed?
Although we guarantee a minimum purity standard of >85%, some of the proteins we prepared have a purity of 95% or even 97%.
How should I reconstitute and store the products?
As for short-term storage or usage, please use sterile deionized water to completely reconstitute proteins to 0.1-1.0 mg/mL. Aliquot after 10-15 minutes if needed and store at 4℃.
As for long-term storage, the cytokines or recombinant proteins are recommended to add 5-50% of glycerol (final concentration) and aliquot for long-term storage at -20℃/-80℃. Our default final concentration of glycerol is 50%. Customers could use it as reference.
What types of tags do you use for fusion?
What is the impact of a given tag type and any potential biological activity of the protein?
Can you remove the endotoxin?
Can you offer aseptic manufacture processing?
How to determine species cross-reactivity of cytokines?
b. Many mouse cytokines may also have effect on human cells, however, the activity may be lower than the corresponding human cytokines.
c. One of the few human cytokines will be more active than corresponding mouse cytokines when acting on mouse cells, such as IL-7.
d. Interferon, GM-CSF, IL-3 and IL-4 and other cytokines are species-specific and almost have no activity on non-homologous cells.
e. In contrast, fibroblast growth factor (FGF) and neurotrophin are highly conserved and both have good activity on cells of different species.
What is the general preservative? Which kind of preservative do you usually add?
What is the general protectant? What kind of protectant do you usually add?
Can’t Find What You’re Looking For? We can help you source the best match or customize a recombinant protein solution for your study. Options may include species (human/mouse/rat), protein region/domain (full-length vs fragment), tag or label (His/GST/FLAG/biotin/fluorescent), expression system (E. coli/HEK293/insect), purity grade, formulation (buffer, carrier-free, glycerol-free), activity/functional validation (binding or enzymatic assays), endotoxin level (low-endotoxin for cell-based work), mutants/variants (point mutations, isoforms), and bulk or custom packaging. Click Talk to a Scientist to submit a request form, email us at support@biohippo.com, or explore our Research Services for additional support. Our team will be in contact with you shortly.
