Recombinant Human Low affinity immunoglobulin gamma Fc region receptor III-A (FCGR3A) is produced in mammalian cells, which appears to help ensure proper folding and post-translational modifications. The extracellular domain spans amino acids 17-208 and comes with a C-terminal 6xHis tag for purification. This protein achieves purity levels above 95% when analyzed by SDS-PAGE. Endotoxin levels stay below 1.0 EU/µg. The protein shows biological activity by binding human CD16a-His (V176) with a 0.571 µM affinity constant in BLI assays.
FCGR3A, which researchers also call CD16a, acts as a receptor for the Fc region of immunoglobulin G (IgG). It plays what seems to be a critical role in antibody-dependent cellular cytotoxicity (ADCC). Natural killer (NK) cells express this receptor primarily, though macrophages and some T-cell subsets also show expression. The receptor appears crucial for mediating immune responses. Understanding how FCGR3A works and interacts with other molecules may prove important for research into immunological pathways and therapeutic antibody development.
Potential Applications
Note: The applications listed below are based on what we know about this protein's biological functions, published research, and experience from experts in the field. However, we haven't fully tested all of these applications ourselves yet. We'd recommend running some preliminary tests first to make sure they work for your specific research goals.
1. IgG-Fc Receptor Binding Affinity Studies
This recombinant FCGR3A extracellular domain could work as a standardized tool for studying binding interactions between various IgG subclasses and CD16a. Surface plasmon resonance or bio-layer interferometry assays might benefit from such standardization. The binding affinity to human IgG1 Fc (0.571 μM) offers a reference point for comparing other immunoglobulin variants or engineered antibodies. Scientists can examine how changes to antibody Fc regions alter CD16a binding kinetics and thermodynamics. High purity and low endotoxin levels make the protein suitable for quantitative biophysical measurements that demand consistent protein quality.
2. Antibody-Dependent Cellular Cytotoxicity (ADCC) Mechanism Research
Scientists might use the recombinant CD16a extracellular domain in cell-free biochemical assays to study ADCC initiation without dealing with complex whole-cell systems. Different therapeutic antibodies or antibody-drug conjugates can be tested for their interaction with this Fc receptor. The His-tag allows for immobilization in pull-down experiments or ELISA-based binding studies. Mammalian expression likely ensures proper glycosylation patterns that could influence binding specificity and affinity measurements. This approach allows controlled analysis of the antibody-receptor interaction that happens before NK cell activation in ADCC responses.
3. Fc Receptor Competitive Binding Assays
The C-terminal His-tagged FCGR3A appears useful for developing competitive binding assays. These could screen libraries of antibody variants or small molecule inhibitors that affect Fc-FcγR interactions. The established binding affinity gives researchers a baseline for measuring competitive displacement by test compounds in microplate-based or biosensor formats. Scientists can attach the protein through the His-tag and measure how different molecules compete with IgG1 Fc for binding sites. Such assays may help researchers understand what structural features are needed for Fc receptor engagement and identify compounds that change immune complex formation.
4. Structural Biology and Protein-Protein Interaction Studies
This soluble FCGR3A extracellular domain looks promising for structural studies aimed at understanding CD16a-antibody complexes. X-ray crystallography or cryo-electron microscopy could provide insights. The high purity and defined expression region (17-208aa) give researchers a uniform protein sample that might work well for crystallization trials with various IgG Fc fragments. The His-tag helps with protein purification and can orient the protein properly in atomic force microscopy or single-molecule studies. Co-crystallization experiments with different antibody Fc variants could reveal the molecular details that determine binding specificity and affinity differences.
5. Fc Engineering and Antibody Optimization Research
The recombinant protein appears valuable for testing engineered antibodies with modified Fc regions designed to enhance or reduce CD16a binding. Scientists developing new therapeutic antibodies can use this standardized FCGR3A preparation to check how specific amino acid changes in the Fc domain affect receptor binding through systematic kinetic analysis. The consistent biological activity and mammalian glycosylation pattern suggest that binding measurements reflect interactions that actually occur in the body. This application seems particularly useful for antibody engineering projects focused on improving effector functions or creating antibodies with reduced immunogenicity.
