Plasmid Name
pHC-IgG1-G236A
Mutation Set
G236A
Selection Marker
Ampicillin
Promoter
CMV
Fc Engineering Overview
The human IgG1 (G236A) Fc variant introduces a single amino acid substitution engineered to selectively increase binding affinity for the activating receptor FcγRIIa over the inhibitory receptor FcγRIIb. This modification drives macrophage-mediated antibody-dependent cellular phagocytosis (ADCP) while maintaining baseline NK cell ADCC activity and standard FcRn recycling.
Functional Profile
| Property | Effect |
|---|---|
| FcγRIIa binding (H131 & R131) | Enhanced ↑↑ (>6× affinity boost) |
| FcγRIIa / FcγRIIb ratio | Substantially Increased ↑↑↑ (Selective activation) |
| ADCP (Phagocytosis) | Strongly Enhanced ↑↑↑ (Macrophage-Dominant) |
| FcγRIIIa binding / ADCC | Moderate / WT Baseline |
| CDC | WT Baseline to Mild Reduction |
| FcRn binding & half-life | Normal / WT Baseline |
| Effector Potency | Selective ADCP-Dominant (High FcγRIIa/FcγRIIb selectivity) |
Mechanism of Action
The G236A variant replaces glycine at position 236 in the lower hinge region of the CH2 domain with alanine (Gly236 to Ala):
- G236A Substitution: Restricts local polypeptide backbone flexibility and introduces favorable hydrophobic interactions specifically tuned to the binding pocket of activating FcγRIIa.
G236A enhances affinity for FcγRIIa without a proportional increase in binding to the structurally homologous inhibitory receptor FcγRIIb, significantly elevating the activating-to-inhibitory (A/I) ratio.
Phenotypic Effects
- Selective enhancement of macrophage and neutrophil recruitment for tumor cell phagocytosis (ADCP).
- Significantly improves the FcγRIIa/FcγRIIb binding ratio to overcome inhibitory signaling on myeloid cells.
- Preserves standard FcRn-mediated recycling and systemic pharmacokinetics.
- Distinguishes ADCP-driven clearance pathways from purely NK cell-mediated ADCC.
Applications
- Therapeutic antibodies targeting solid tumors where myeloid/macrophage infiltration dominates over NK cells.
- Macrophage-checkpoint target depletion requiring pure phagocytic enhancement without excessive NK cell hyperactivation.
- Dissecting cellular effector mechanisms (ADCP vs. ADCC) in preclinical models.
Plasmid Map & Feature Annotation
Insert Structure: VH – CH1 – hinge – CH2(G236A) – CH3
- VH: Variable heavy domain
- CH1: Constant heavy 1
- Hinge: Native IgG1 hinge
- CH2 (G236A): Selective ADCP-enhancing single mutation
- CH3: Native IgG1 CH3 domain
Product Note: While multi-mutation variants like GASDALIE include G236A as part of a high-affinity cluster, the isolated G236A single mutant serves as the core module for selective phagocytosis enhancement. Note that this substitution is distinct from the deletion variant ΔG236, which completely abolishes FcγR engagement (Effector-Null).
Fusion BioLabs ADCC/ADCP-Enhanced Family Comparison Matrix
| Variant | Mechanism | Enhancement Strength | Primary Application & Notes |
|---|---|---|---|
| human IgG1 (WT) Wild-Type |
Native baseline FcγR binding | ★★☆☆☆ | Baseline Control. Standard physiological FcγR binding and ADCC/ADCP baseline for comparative assays. |
| human IgG1 (G236A) G236A |
Lower hinge FcγRIIa selective optimization | ★★★☆☆+ | This Product. Selective ADCP Enhancer. Specifically boosts macrophage phagocytosis by maximizing the FcγRIIa/FcγRIIb activation ratio. |
| human IgG1 (DE) S239D / I332E |
CH2 domain electrostatic interface enhancement | ★★★☆☆ | Moderate ADCC/ADCP Enhancer. Core double mutation boosting FcγRIIIa and FcγRIIa engagement. |
| human IgG1 (DLE) S239D / A330L / I332E |
CH2 domain structural interface enhancement | ★★★★☆ | Strong ADCC Enhancer. Classic triple mutation optimizing NK cell-mediated lysis. |
| human IgG1 (ADE) G236A / S239D / I332E |
CH2 domain multi-residue FcγRIIIa optimization | ★★★★☆+ | High-Potency ADCC/ADCP Enhancer. Increases FcγRIIIa binding while improving the FcγRIIa/FcγRIIb binding ratio to favor activation over inhibition. |
| human IgG1 (GASDALIE) G236A / S239D / A330L / I332E |
CH2 domain hyper-enhancement (FcγRIIIa & FcγRIIa) | ★★★★★ | Ultra-Potent ADCC/ADCP Enhancer. Maximum engineered affinity variant for low antigen density targets. |
Storage & Handling
- Store plasmid at −20°C.
- Avoid repeated freeze–thaw cycles.
- Use sterile technique when handling.
- Suitable for transient or stable mammalian expression.
References
- Yamane-Ohnuki N, Satoh M. Production of therapeutic antibodies with controlled fucosylation. MAbs. 2009;1(3):230-236.
- Richards JO, Karki S, Lazar GA, Chen H, Dang W, Desjarlais JR. Optimization of antibody binding to FcgammaRIIa enhances macrophage phagocytosis of tumor cells. Mol Cancer Ther. 2008;7(8):2517-2527.
