Wide range of recombinant proteins
We offer a diverse and wide range of recombinant proteins essential for understanding the relationship between protein structure and function, as well as their implications in various diseases. Our proteins are produced to a high purity in several expression systems, with low endotoxin levels and quality checks for biological activity. St John's Laboratory is ready to provide you with all the protein tools you need to advance your research.
Premium quality recombinant proteins at competitive prices
- High purity and homogeneity: Recombinant proteins are produced to high purity levels, providing you with full confidence in your research results.
- Defined bioactivity: Enhance the efficacy of your research applications with our rigorously tested recombinant proteins.
- Low endotoxin levels: Low endotoxin levels applicable across many products - Less than 0.1 ng/µg (1EU/µg) in each batch of recombinant proteins as assessed by the Limulus Amoebocyte Lysate (LAL) assay.
Range of Interleukins, TNFs, GM-CSF
EGFR, HER2, PD1, PD-L1 and CD markers
Biotin, Avi-tag, His-tag and Fc fusion conjugates
Recombinant fragments of p24, Influenza, Zika and more
Recombinant Proteins & Peptides
Plan experiments with confidence: pick the right expression system, verify QC attributes (purity, bioactivity, endotoxin), choose the best tag/conjugation, and prepare/reconstitute correctly. Below are application‑driven panels (cytokines, immuno‑checkpoints, viral antigens, stem cell & organoid factors) tied to your catalogue.
Cytokines & Growth Factors
Core proteins for immune cell culture, differentiation and functional assays. Pair with validated bioactivity data where applicable.
Cytokines are a family of small glycoproteins that play crucial roles in cell signalling in the immune system and other processes. By binding to specific receptors on target cells, cytokines trigger signal transduction pathways, regulating gene expression and protein production. Maintaining optimal cytokine levels is a delicate balance. While cytokines are essential for immune responses, dysregulation can lead to pathological inflammation, contributing to autoimmune diseases and cancer.
Advance your research into cytokines with our range of recombinant cytokine proteins.
| Target | Typical use | Notes | Browse |
|---|---|---|---|
| IL‑2 | T cell expansion | High‑specific‑activity preferred | Recombinant IL‑2 |
| IL‑7 | T cell survival/homeostasis | Combine with IL‑2 or IL‑15 | Recombinant IL‑7 |
| IL‑6 | Differentiation/acute phase | Species‑matched receptors | Recombinant IL‑6 |
| GM‑CSF (CSF2) | Monocyte→DC differentiation | Often with IL‑4 | Recombinant GM‑CSF |
| BMP4 / Activin A | Lineage specification | Mesendoderm induction | Recombinant Activin |
| Wnt3a / R‑spondin | Organoid media | Check carrier‑free for media making | Recombinant Wnt/RSPO |
Cell‑Surface & Checkpoint Proteins
Extracellular domains & Fc fusions for binding/neutralization assays, CAR screening, and receptor–ligand studies.
At St. John's Laboratory, we are dedicated to delivering high-quality recombinant cell surface proteins that play a crucial role in advancing cancer research. Our offerings for key cell surface markers, include a variety of CD antigens (such as CD10, CD20, CD30, CD31, CD40, and CD48), support investigations into cell-cell interactions, immune regulation, and the complexities of tumour biology. Our recombinant proteins support cancer research, particularly those focusing on CAR-T/CAR-NK cell therapies and the development of new antibody-based treatments. For example:
- Recombinant HER2 (Human Epidermal Growth Factor Receptor 2) is widely used to study its overexpression in breast and gastric cancers. These proteins facilitate the screening and development of targeted treatments, such as monoclonal antibodies and small-molecule inhibitors.
- Recombinant PD-1 and PD-L1 (Programmed Cell Death Protein 1 and its ligand) play a pivotal role in investigating immune checkpoint blockade, a groundbreaking method in cancer immunotherapy.
Researchers utilise these proteins to explore their binding interactions, discover new immune-modulating agents, and understand how tumours evade immune detection. Furthermore, recombinant EGFR (Epidermal Growth Factor Receptor) is extensively utilised to study its abnormal signalling in various cancers, including lung, colorectal, and head and neck cancers, aiding in the development of tyrosine kinase inhibitors and other antibody-based therapies.
| Target | Application | Notes | Browse |
|---|---|---|---|
| PD‑1 / PD‑L1 | Checkpoint blockade studies | Use matched species; consider Avi‑biotin for BLI | PD‑1/PD‑L1 |
| CTLA‑4 (CD152) | Checkpoint binding | Fc‑fusion increases avidity | CTLA‑4 |
| EGFR / HER2 | Receptor–ligand assays | Glycosylation affects binding | EGFR/HER2 |
| CD19 / CD20 | B‑cell targets, CAR screens | Use native‑like ECDs | CD19/CD20 |
| 4‑1BB (CD137) / OX40 | Costimulatory interactions | Fc or Avi‑biotin for capture | CD137/OX40 |
Stem Cell & Organoid Factors
Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) possess the unique capability of self-renewal and can differentiate into lineages derived from all three germ layers. This characteristic makes them up-and-coming candidates for regenerative therapies in treating various diseases. Notably, iPSCs have the added advantage of minimal or no immune rejection.
Organoids are becoming increasingly important in drug development. Those derived from stem cells offer a more physiologically relevant alternative to traditional 2D cultures and animal models in preclinical drug testing. Organoids are derived from stem cells, and the use of recombinant cytokines and growth factors is essential for advancing organoid technology. These molecules play a key role in regulating the intricate processes of self-organisation, proliferation, and differentiation. This allows organoids to closely resemble the structure and function of their natural counterparts in the body. Additionally, recombinant proteins are crucial for developing and maintaining the stem cell niche and for maturing into functional tissues that accurately replicate human physiology for research purposes.
Hematopoietic stem cells (HSCs) are multipotent cells that can differentiate into all types of blood cells. Cytokines and growth factors direct HSC differentiation down either the lymphoid lineage (to produce T cells, B cells, and NK cells) or the myeloid lineage (to produce neutrophils, macrophages, and dendritic cells).
Pluripotency maintenance and lineage‑specific organoid growth. Choose carrier‑free for media formulations.
Stem cells possess an extraordinary capacity for self-renewal and can transform into various cell types during early development. They are primarily classified into two categories: pluripotent stem cells, which include both embryonic and induced pluripotent stem cells, and adult (or somatic) stem cells. In a research setting, the precise growth and differentiation of these stem cells are orchestrated by recombinant growth factors and cytokines. These engineered proteins act as vital external cues, mimicking the natural biological signals that cells encounter in the body.
| Factor | Culture use | Notes | Browse |
|---|---|---|---|
| TGF‑β1 / Activin A | Pluripotency and early lineage cues | Activity validated in SMAD assays | TGF‑β/Activin |
| Noggin | Brain/intestine/pancreas organoids | Pairs with RSPO/Wnt | Noggin |
| Wnt3a / R‑spondin | Intestinal/liver/retina organoids | Confirm activity lot‑to‑lot | Wnt/RSPO |
| BMP4 | Liver/kidney organoids | Use time‑limited pulses for patterning | BMP4 |
Expression Systems
Pick an expression host that matches your downstream application (PTMs, folding, activity, scalability).
| System | PTMs | Strengths | Considerations |
|---|---|---|---|
| HEK293 (human) | Human‑like glycosylation | Best for receptors & Fc fusions; native folding | Higher cost than bacterial |
| CHO (mammalian) | Mammalian glycosylation | Therapeutic‑grade workflows; robust secretion | Cost & time |
| Insect (Sf9/Sf21) | Limited glycosylation | High yields for secreted/extracellular domains | Glycan patterns differ from human |
| E. coli | No glycosylation | Very scalable; cost‑effective | May require refolding; endotoxin control |
| Yeast (Pichia) | High‑mannose glycans | Secreted yields; simple media | Non‑human glycans affect binding for some proteins |
Quality & QC Attributes
Key specs to check before ordering — ensures reproducibility and regulatory‑friendly data.
| Attribute | Typical spec / info | Why it matters |
|---|---|---|
| Purity | ≥95% by SDS‑PAGE/HPLC | Minimizes off‑target effects and assay interference |
| Endotoxin | ≤1 EU/µg (≤0.1 ng/µg) by LAL | Critical for cell culture & immune assays |
| Bioactivity | Cell‑based EC50; ligand/receptor binding (SPR/BLI) | Confirms functional performance |
| Sequence & tag | Uniprot ref; signal peptide; His/Fc/GST; Avi‑biotin | Assay compatibility and capture/immobilization |
| Formulation | Carrier‑free or with BSA/Trehalose | Impacts conjugations and some assays |
| Storage | Aliquot at −80 °C; avoid ≥3 freeze‑thaws | Preserves activity across experiments |
Formulation & Storage
Match formulation to your assay. Use carrier‑free for conjugation; choose stabilizers for long‑term storage and low abundance dosing.
| Formulation | Pros | Considerations |
|---|---|---|
| Carrier‑free (no BSA) | Ideal for conjugation & biophysics | Use low‑protein bind tubes; add trehalose if storing |
| With carrier (BSA, trehalose) | Improves stability against adsorption | Not suitable for some conjugations/assays |
| Lyophilized | Room‑temp shipping; long shelf‑life | Follow reconstitution instructions carefully |
| Liquid (frozen) | Ready to use | Aliquot; avoid repeat freeze‑thaw |
Reconstitution & Dosing (Quick Guide)
Use sterile buffers (PBS, water) with carrier protein if recommended. Spin vials before opening. Below are example volumes.
| Vial content | Target concentration | Add this volume | Notes |
|---|---|---|---|
| 10 µg | 0.1 mg/mL | 100 µL diluent | Gives 100 µL at 100 µg/mL |
| 50 µg | 0.5 mg/mL | 100 µL diluent | Gives 100 µL at 0.5 mg/mL |
| 100 µg | 0.2 mg/mL | 500 µL diluent | Aliquot for single‑use |
| 1 mg | 1 mg/mL | 1 mL diluent | Prepare working stocks as needed |
Assay Standards & Controls
Controls improve quantitation and troubleshooting across ELISA, BLI/SPR, neutralization and cell‑based assays.
| Type | Where used | Notes |
|---|---|---|
| Calibrators/standards | ELISA, qPCR protein calibration | Define dynamic range & LOD |
| Capture antigens | ELISA plates, serology | Choose tag/biotin for orientation |
| Ligand/binding pairs | BLI/SPR kinetics | Avi‑biotin + streptavidin sensor |
| Neutralization controls | Cell‑based assays | Active cytokines + blocking antibodies |
Protein FAQs
Quick answers to common protein questions.
| Question | Answer |
|---|---|
| Carrier‑free or with carrier — which should I pick? | Use carrier‑free for conjugations/biophysics. Choose with carrier (e.g., BSA/trehalose) for long‑term storage or low‑adsorption dosing; note that carriers can interfere in some assays. |
| What endotoxin level is acceptable for cell culture? | For sensitive immune assays, aim for ≤1 EU/µg protein measured by LAL. Lower is better; always confirm the lot‑specific COA. |
| How do I avoid protein loss from adsorption? | Use low‑bind plastics, include carrier protein if compatible, and avoid repeated freeze‑thaw by aliquoting upon first thaw. |
Need help selecting a protein?
Tell us your assay (cell‑based, ELISA, BLI/SPR), species, tag preference, and instrument — we’ll recommend proteins that fit and share lot‑specific QC.