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Human OX40 (CD134) Protein (C-His)

Human OX40 protein (C-His) on SDS-PAGE under reducing condition (P+) and non-reducing condition (P-). The gel was stained for 1 hour with BlinkBlue (catalog 700102). The purity of this protein appears to be greater than 95% based on reducing conditions.

Cat #	Size	Price	Quantity
817901	25 ug	$145
817902	100 ug	$295

Bulk/Custom

Product Details

Application	ELISA, BLI
Format	Liquid, Purified
Expression Host	CHO
Target Name	TNFRSF4, OX40, CD134, OX40L receptor
Species	Human
Sources	Recombinant Human OX40 (Lue29-Ala216) with C-terminus His-tag is expressed in CHO cell.
Accession Number	P43489
Molecular Weight	The protein has a predicted molecular weight of 21.7 kDa. Under DTT-reducing conditions, it migrates at approximately 40 kDa on SDS-PAGE.
Affinity Tag	C-His
Purity	>95% based on SDS-PAGE under reducing condition
Regulatory Status	RUO
Formulation	1xPBS buffer, pH7.4, 0.22 µm filtered
Endotoxin level	Not tested
Protein Concentration	25µg size is bottled at 0.2mg/mL concentration. 100 µg size is supplied at a lot-specific concentration.
Storage and Handling	Briefly centrifuge the vial upon receipt. An unopened vial can be stored at 4°C for up to 2 weeks, or at -20°C or below for up to six months. The protein may be further diluted to 0.1 mg/mL using 0.22 µm-filtered PBS buffer (pH 7.4). For long-term storage, the diluted stock solution should be aliquoted and stored at ≤ –70°C to minimize freeze-thaw cycles. If additional dilution is required, carrier proteins such as FBS or BSA should be added to maintain protein stability.
Research Areas	Co-stimulation, Activated T cells, Tregs, Activated NK cells, Neutrophils, Activated Dendritic cells, Autoimmunity

Background Information

OX40, also known as CD134 or TNFRSF4, is a co-stimulatory receptor that plays a key role in regulating T cell activation, survival, and memory formation. OX40 is not expressed on resting naïve T cells but is rapidly upregulated on CD4⁺ and CD8⁺ T cells following antigen recognition and co-stimulation. It is also expressed on regulatory T cells and, in some contexts, on innate immune cells. Through its signaling, OX40 enhances the magnitude and durability of adaptive immune responses.

Structurally, OX40 is a type I transmembrane glycoprotein and a member of the tumor necrosis factor receptor (TNFR) superfamily. Its extracellular region contains multiple cysteine-rich domains characteristic of TNFR family members, which mediate ligand binding. OX40 has a single transmembrane domain and a cytoplasmic tail that lacks intrinsic enzymatic activity but recruits TNF receptor–associated factors (TRAFs) upon activation. These adaptor proteins initiate downstream signaling pathways, including NF-κB, PI3K–AKT, and MAPK pathways, which promote T cell proliferation, survival, and cytokine production.

The primary ligand for OX40 is OX40 ligand (OX40L, also known as CD252 or TNFSF4), which is expressed on activated antigen-presenting cells such as dendritic cells, B cells, and macrophages, as well as on endothelial cells in inflamed tissues. Engagement of OX40 by OX40L delivers a potent co-stimulatory signal that supports clonal expansion of effector T cells, enhances the generation of long-lived memory T cells, and can modulate the suppressive function of regulatory T cells.

OX40 signaling is implicated in a range of disease processes. In autoimmune and inflammatory diseases, excessive or prolonged OX40–OX40L interactions can drive pathogenic T cell responses, contributing to chronic inflammation and tissue damage. In allergic disease, OX40 promotes Th2 differentiation and cytokine production, supporting allergic inflammation. Conversely, in cancer, insufficient OX40 signaling may limit effective anti-tumor immunity, as robust T cell activation and persistence are required for tumor control.

Therapeutically, OX40 is an active target of immunomodulatory strategies. Agonistic antibodies targeting OX40 are being developed to enhance T cell responses in cancer immunotherapy, often in combination with immune checkpoint inhibitors to improve efficacy. In contrast, blockade of the OX40–OX40L pathway is being explored as a potential treatment for autoimmune and inflammatory diseases. These dual approaches underscore OX40’s central role in balancing immune activation and regulation in health and disease.

Frequently Asked Questions

How is a fluorescence labeled recombinant protein different from a labeled antibody for the same target?

A labeled protein (e.g., a fluorescent ligand or receptor domain) binds its natural counter-receptor or binding partner directly, making it useful for functional binding assays, competition/blocking studies, and receptor occupancy measurements — whereas an antibody typically binds a specific epitope regardless of the protein's natural binding activity. Choose the labeled protein format when you need to assess biologically relevant binding interactions rather than simple target detection.

Can these proteins be used in flow cytometry, and are they compatible with other panel reagents?

Yes, fluorescence labeled proteins are commonly used in flow cytometry panels to detect receptor expression or ligand binding on live cells, and are designed to be compatible with standard antibody panels. As with any multicolor panel, confirm spectral compatibility and run proper compensation controls when combining labeled proteins with labeled antibodies.

What controls should I use with fluorescence labeled recombinant proteins?

Recommended controls include an unlabeled/unconjugated version of the same protein (for competition/blocking controls), an irrelevant labeled protein of the same conjugate as a background control, and standard unstained/FMO controls for gating. Species- or format-matched controls are noted on the product page where available.

What applications are these proteins validated for?

Common applications include receptor binding assays, flow cytometry-based ligand-receptor studies, ELISA-based detection, and blocking/competition assays to study receptor occupancy or antagonist activity. Specific validated applications and recommended usage concentrations vary by product and are detailed on the individual product page.

Have a product or application question? Consult our FAQs or contact us.

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