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Proteins

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Recombinant and native proteins across four expression systems for every application

Find purified proteins for your ELISA standards, cell-stimulation reagents, Western blot controls, and immunisation antigens. The range covers recombinant proteins made in mammalian, insect, yeast, and bacterial systems for your workflow, plus native proteins isolated from biological sources. Ready-to-use kits for protein labelling and quantification complete the range you need.

Recombinant proteins cover cytokines and growth factors, transcription factors, signalling kinases, proteases, and structural proteins. These span human, mouse, rat, and viral species. The catalogue extends to more than 14,000 human and mouse targets, confirmed for purity by SDS-PAGE. Both tagged (His-tagged, GST-tagged, Fc-fusion, FLAG/HA-tagged) and untagged recombinant proteins are available to you.

Custom production is available for targets outside the standard range, giving you a route to proteins that are not yet catalogued. Protein labelling kits, including enzymatic biotinylation for site-specific tagging, cover your conjugation needs. For concentration measurement, BCA, Bradford, and GFP-specific quantification kits cover the main sample types.

The decision follows this order.

  1. Application. Reference standards, positive controls, and diagnostic assay development and validation call for Native Proteins. Enzymatic and binding assays, signalling-pathway analysis, and assay or kit development call for Recombinant Proteins. Your Biotin-tagged protein work points to Protein Labelling. Measuring the concentration of a sample or lysate before downstream work points to Protein Quantification.

  2. Expression system. Mammalian-expressed proteins suit your bioassays that need native post-translational modifications. Bacterial-expressed proteins suit structural and biochemical assays where glycosylation is not required.

  3. Species. Protein species matches your cell or animal model species: human proteins suit human cell assays, mouse proteins suit primary murine cell stimulation. Cross-species receptor binding reduces potency.

  4. Tag. His-tags suit purification on Ni-NTA resins and most of your pull-down assays. Biotinylated proteins enable streptavidin-mediated capture for SPR, biolayer interferometry, and oriented pull-down assays. Untagged, native proteins suit work where any tag would interfere with structure or activity.

  5. Purified recombinant proteins
    Native proteins
    Protein labelling kits
    Protein quantification kits

Applications

Cytokine stimulation and receptor activation assays

Recombinant cytokines drive signalling cascades in primary cells. The CoA carries glycoform data for your glycan-sensitive work.

Structural biology and biophysics

Highly pure recombinant proteins support your X-ray crystallography, cryo-EM, and SPR studies. Expression host and tag removal affect purity.

Protein-protein interaction studies

Biotinylated proteins on streptavidin surfaces enable pull-down and biolayer interferometry with defined orientation, giving you quantitative binding data.

Assay development and calibration

Low-endotoxin recombinant proteins serve as positive controls and calibrators in sandwich ELISA assays, giving your assays consistent lot-to-lot performance.

Native protein use

Native protein preserves post-translational modifications and isoforms reflecting physiological conditions, suiting your reference standards and diagnostic validation.

Immunisation and antibody generation

Purified recombinant and native antigens raise high-titre responses for your polyclonal and monoclonal antibody production, including custom targets.

Frequently asked questions

What expression system should I choose for a recombinant protein: bacterial, mammalian, or insect?

Bacterial expression (E. coli) is fastest and least expensive. It works well for structural and biochemical studies where glycosylation is not required. Mammalian systems such as HEK293 or CHO give mammalian-like glycosylation and disulfide processing. This can matter for cytokine bioactivity and receptor binding.

Glycosylation is not always identical to the endogenous tissue, disease state, or isoform. Check the host, glycoform data, and activity on the CoA or datasheet for glycan-sensitive applications. Insect cell expression (Sf9 via baculovirus) gives higher yields than mammalian systems, with partial glycosylation. It suits many structural and enzymatic studies.

 Why does endotoxin level matter for cell-based assays?

Lipopolysaccharide (endotoxin) is a potent activator of the innate immune response. It works via TLR4 signalling in monocytes, macrophages, and dendritic cells. Even sub-nanogram quantities per millilitre trigger cytokine release, NF-kB activation, and apoptosis in sensitive primary cells.

These effects mask or confound the biological effect of the protein being tested. Cell culture assays therefore need low-endotoxin or endotoxin-tested protein preparations, typically below 1 EU per microgram.
How should I determine the active concentration of a recombinant protein?

Total protein concentration measured by absorbance at 280 nm or Bradford assay does not distinguish active from inactive or aggregated species. The best way to find active concentration is a cell-based bioassay. This should report on the specific receptor or pathway the protein activates, with EC50 compared to a reference standard.

For enzymes, specific activity (units per milligram) is the relevant metric. Measure it with the appropriate substrate under defined conditions.

Product catalogs

Not sure which catalog to start with? We will help you find the right products.

Tell us what you are looking for — antibodies, kits, proteins, or supplies — and our team will point you to the best catalog filters, suppliers, and product matches for your workflow.

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