Recombinant Proteins

Recombinant Protein Categories

Recombinant proteins in our range are organised by biological role and application, from soluble cytokines used in cell culture to membrane receptor ectodomains used in binding and capture assays. Choose a category below to browse that part of the range.

Active EGFR and Biotinylated PD-L1: Two Functionally Validated Proteins

EGFR and PD-L1 anchor two of the most studied pathways in cancer research: receptor tyrosine kinase signalling and T cell checkpoint inhibition. Both proteins below are supplied with functional assay data confirming ligand or antibody binding, not purity data alone.

EGFR · HEK293 · Active

Human EGFR Protein (Active Recombinant, C-His) (STJP000982)

Produced in HEK293 cells spanning the Met1-Ser645 region with a C-terminal His tag, and less than 0.1 EU/µg endotoxin by LAL method. Binding activity is confirmed by functional ELISA, where immobilised EGFR captures its ligand EGF across a 7-25 ng/mL linear range. EGFR is a receptor tyrosine kinase that activates the RAS-RAF-MEK-ERK and PI3K-AKT cascades on ligand binding, and is a well-established driver in several solid tumour types.¹

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PD-L1/CD274 · HEK293 · Biotin

Human PD-L1/B7-H1 Protein (C-His-Avi, Biotin) (STJP001643)

Site-specifically biotinylated through the Avi-tag/BirA system for defined-orientation capture, with purity above 95% by SEC-HPLC and a dose-response EC50 of 2.8 ng/mL against an anti-PD-L1 antibody by ELISA. PD-L1 engagement of PD-1 delivers an inhibitory signal that limits T cell activation and proliferation, a pathway central to checkpoint blockade research.²

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Cytokines and Growth Factors

Cytokines are small secreted proteins that regulate cell signalling in the immune system and beyond, binding specific receptors to trigger transduction pathways that control gene expression. Interleukin-2 (IL-2) drives T cell proliferation and, together with its receptor subunits CD25 (IL-2RA) and CD122 (IL-2RB), is used to study T cell growth signalling and regulatory T cell homeostasis.³ IL-4, IL-6 and IL-7 cover Th2 differentiation, acute-phase and B cell responses, and T cell survival signalling respectively, GM-CSF drives monocyte to dendritic cell differentiation, and type I interferon IFN-alpha 2 supports antiviral and innate immune signalling studies.

Immune Checkpoint and Costimulatory Proteins

PD-1 and its ligand PD-L1 form the checkpoint axis exploited by tumours to blunt cytotoxic T cell activity.² CTLA-4 acts further upstream in T cell priming, competing with CD28 for the CD80/CD86 ligands on antigen-presenting cells and functioning as an essential negative regulator of T cell responses.⁵ CD28 itself delivers the costimulatory signal required alongside T cell receptor engagement for full T cell activation.⁵

Cancer and Receptor Tyrosine Kinase Signalling

EGFR (ErbB1/HER1) and HER2 (ErbB2) belong to the same four-member receptor tyrosine kinase family and frequently dimerise together in tumour cells, with the EGFR-HER2 heterodimer among the most robust signalling pairs in the family despite HER2 having no known ligand of its own.¹ EGFRvIII is a constitutively active deletion variant of EGFR that removes part of the ligand-binding domain and recurs in glioblastoma research models.

Vascular and Angiogenesis Research

VEGFR-2 (KDR/CD309) is the principal receptor mediating VEGF-driven endothelial cell proliferation, migration and new vessel formation, and is regulated through a layered system of receptor-interacting proteins, endocytosis and intracellular trafficking.⁴

Viral Antigens

Viral antigens in our range are produced from defined strain or variant sequences for use in serology, ELISA coating and cross-reactivity studies, with lot-to-lot consistency confirmed on the product datasheet. Antigens from different strains or variants can differ substantially in their antigenic, functional and structural properties, so tag position and strain should be checked against the assay before ordering. The range covers SARS-CoV-2 and its variants, MERS, HIV, hepatitis B and C, cytomegalovirus and H5N1 avian influenza.

Stem Cell and Organoid Factors

Embryonic and induced pluripotent stem cells self-renew and can differentiate into lineages from all three germ layers, and their growth and differentiation in culture are directed by recombinant growth factors and cytokines that mimic the natural signals cells encounter in the body. Organoids, which are derived from stem cells, offer a more physiologically relevant alternative to 2D culture for preclinical work, and depend on the same class of recombinant factors to regulate self-organisation, proliferation and differentiation. Haematopoietic stem cells are directed down the lymphoid lineage, producing T cells, B cells and NK cells, or the myeloid lineage, producing neutrophils, macrophages and dendritic cells, according to the cytokine and growth factor signals they receive.

Tags and Conjugation Options

Recombinant proteins in our range are supplied unconjugated or conjugated to a range of tags, depending on the assay. Affinity tags such as 6xHis, GST and FLAG support purification and capture, while Fc fusions to human IgG1 improve stability and can increase avidity through dimerisation. Site-specific biotinylation through the Avi-tag/BirA system labels a single defined lysine residue, giving a consistent biotin to protein ratio for streptavidin-based capture. Tags are positioned at either the N- or C-terminus of the protein depending on the target and are stated on the product datasheet.

Expression Systems

The expression host determines the post-translational modifications a protein carries, which in turn affects folding, activity and how directly the result translates to a native human target. Choose a host that matches the downstream application.

Quality and QC Attributes

Every recombinant protein datasheet states the expression system, tag position, purity method and endotoxin result for that specific lot, so the specifications below describe what the majority of the range is produced to rather than a guarantee for every individual product.

Formulation and Storage

Match formulation to the assay: carrier-free protein suits conjugation and biophysical work, while a stabiliser suits long-term storage or low-abundance dosing.

Reconstitution and Dosing

Use sterile PBS or water, with carrier protein where recommended on the datasheet, and spin vials briefly before opening. The volumes below are typical starting points.

Assay Standards and Controls

Controls improve quantitation and troubleshooting across ELISA, BLI/SPR, neutralisation and cell-based assays.

Protein FAQs

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