Human PD-L2 (CD273) Protein (C-Fc-Avi)

Product Details


ApplicationELISA, BLI
FormatLiquid, Purified
Expression HostCHO
Target NamePDL2, , Butyrophilin B7-DC, CD273, PDCD1 ligand 2
SpeciesHuman
SourcesRecombinant Human PD-L2 (Leu20-Pro219) with C-terminus Fc-Avi-tag is expressed in CHO cell.
Accession NumberQ9BQ51
Molecular WeightThe protein has a predicted molecular weight of 51.2 kDa. Under DTT-reducing conditions, it migrates at approximately 65-75 kDa on SDS-PAGE.
Affinity TagC-Fc-Avi
Purity>95% based on SDS-PAGE under reducing condition
Regulatory StatusRUO
Formulation1xPBS buffer, pH7.4, 0.22 µm filtered
Endotoxin levelNot tested
Protein Concentration25µg size is bottled at 0.2mg/mL concentration. 100 µg size is supplied at a lot-specific concentration.
Storage and HandlingBriefly 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 AreasHematopoietic Stem cells, Memory B cells, Asthma, Cancer Marker, Immune Checkpoints, Cancer Immunology

Background Information


CD273, also known as programmed death-ligand 2 (PD-L2) or B7-DC, is a transmembrane protein that functions as an immune checkpoint molecule regulating T cell activation and immune responses. CD273 is a member of the B7 family of costimulatory molecules and is primarily expressed on antigen-presenting cells such as dendritic cells, macrophages, and B cells, with expression upregulated during inflammation and immune activation. The protein binds to programmed cell death protein 1 (PD-1) on T cells, delivering inhibitory signals that suppress T cell proliferation, cytokine production, and effector functions. This interaction plays a crucial role in maintaining immune homeostasis, preventing autoimmunity, and resolving inflammatory responses. PD-L2 plays a pivotal role in negative regulation of the adaptive immune response, and unlike its related molecule PD-L1 (CD274), CD273 expression is more restricted and primarily induced under specific inflammatory conditions.

Structurally, CD273 is a type I transmembrane glycoprotein of approximately 25-30 kDa belonging to the immunoglobulin superfamily. The extracellular region contains two immunoglobulin-like domains: an N-terminal IgV-like domain that mediates PD-1 binding and a membrane-proximal IgC-like domain that provides structural support. The protein also contains a single transmembrane domain and a short cytoplasmic tail. Structural studies have revealed the features that distinguish PD-L2 from PD-L1 in their interactions with PD-1. The IgV domain of CD273 interacts with PD-1 through a binding interface similar to that of PD-L1, though CD273 binds PD-1 with approximately 2-6 fold higher affinity than PD-L1. This higher binding affinity allows CD273 to effectively engage PD-1 and deliver coinhibitory signals that modulate T cell responses.

The primary ligand for CD273 is PD-1 (CD279), an inhibitory receptor expressed on activated T cells, B cells, and myeloid cells. PD-1 has two naturally occurring ligands: PD-L1 and PD-L2 (CD273), both identified over a decade ago. The CD273-PD-1 interaction delivers negative regulatory signals that attenuate immune responses. Additionally, CD273 has been reported to bind to repulsive guidance molecule b (RGMb), though the functional significance of this interaction remains under investigation. The binding of CD273 to PD-1 results in recruitment of phosphatases that inhibit T cell receptor signaling pathways, reducing T cell activation and promoting immune tolerance.

In disease contexts, CD273 plays a significant role in cancer immune evasion and is associated with patient prognosis. As an immune checkpoint molecule, PD-L2 was reported to be associated with patient outcomes and plays a pivotal role in cancer cell immune escape. Many tumors upregulate CD273 expression to suppress antitumor T cell responses, contributing to immune evasion. Elevated CD273 expression has been observed in various cancers, including Hodgkin lymphoma, mediastinal B cell lymphoma, and certain solid tumors, where it correlates with immune suppression in the tumor microenvironment. Therapeutically, the evolving landscape of PD-L2 is bringing new light to checkpoint immunotherapy. While most immune checkpoint inhibitors have focused on the PD-1/PD-L1 axis, the PD-1/PD-L2 (CD273) pathway is also being investigated as a therapeutic target. Some anti-PD-1 antibodies such as nivolumab and pembrolizumab block both PD-L1 and PD-L2 binding to PD-1, contributing to their therapeutic efficacy. Additionally, CD273 is being explored as a biomarker for predicting response to immunotherapy, and selective CD273-targeting strategies are under development to modulate immune responses in cancer and autoimmune diseases while potentially minimizing toxicity compared to broader PD-1/PD-L1 blockade.

Data Sheets


Human PD-L2 (CD273) Protein (C-Fc-Avi) TDS

Related Protocols


Direct ELISA Protocol

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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.