Available Configurations & Antibody Expression
Fusion BioLabs offers the Human IgG1 (YTE) Fc Engineering Expression Vector (AFV-06) as a single Fc-engineered heavy-chain vector or an Fc Engineering Set/Pair with a compatible human kappa (κ) or lambda (λ) light-chain expression vector.
For complete Fc-engineered IgG antibody expression, the heavy-chain expression vector must be co-transfected with a compatible light-chain expression vector containing the corresponding antibody VL sequence.
The Fc Engineering Set/Pair includes two separate plasmids (5.0 µg each), supplied individually in TE buffer.
Important: Antibody-specific VH and VL sequences must be cloned into the corresponding vectors unless explicitly supplied with pre-inserted variable regions. Purified antibody is not included.
Compatible light-chain expression vectors are also available separately in the Fusion BioLabs Antibody Expression Vector product category.
Fc Engineering Overview
The Human IgG1 (YTE) Fc variant introduces three coordinated mutations within the CH2 domain designed to enhance FcRn binding at acidic pH and extend serum half-life. Reduced FcγR and C1q interactions also decrease effector function, making YTE ideal for long-acting, low-effector biologics.
Functional Profile
| Property | Effect |
|---|---|
| FcγR binding | Reduced ↓ |
| ADCC | Reduced ↓ |
| CDC | Reduced ↓ |
| FcRn binding | Increased ↑↑ |
| Serum half-life | Extended ↑↑ |
| PK profile | Long-acting |
Mechanism of Action
The YTE Fc variant introduces three coordinated mutations—M252Y, S254T, and T256E—within the CH2 domain. These mutations increase the affinity of IgG1 for FcRn at acidic pH (≈6.0) while maintaining normal dissociation at physiological pH. This enhances Fc recycling and significantly prolongs serum half-life. Reduced FcγR and C1q interactions also decrease effector function, making YTE ideal for long-acting, low-effector biologics.
Phenotypic Effects
- Strongly increased FcRn binding.
- Extended serum half-life (2–4× depending on species).
- Reduced ADCC and CDC.
- Lower FcγR engagement.
- Maintains structural integrity and antigen binding.
- Ideal for long-acting therapeutic antibodies.
Applications
- Long-acting therapeutic antibodies.
- FcRn mechanistic studies.
- PK/PD optimization.
- Antibodies requiring reduced effector function.
- Preclinical development of extended-duration biologics.
Plasmid Map & Feature Annotation
Human IgG1 (YTE: M252Y/S254T/T256E)
Insert Structure: VH – CH1 – hinge – CH2(M252Y/S254T/T256E) – CH3
- VH: Variable heavy domain
- CH1: Constant heavy 1
- Hinge: Native IgG1 hinge
- CH2(M252Y/S254T/T256E): FcRn-enhancing mutations
- CH3: Constant heavy 3
Fusion BioLabs FcRn / PK-Modulated Family Comparison Matrix
| Variant | Mechanism | Strength (PK Extension) | Primary Application & Notes |
|---|---|---|---|
| human IgG1 (WT) Wild-Type |
Native FcRn binding | ★★☆☆☆ | Baseline Control. Standard physiological baseline (~21-day half-life in humans). |
| human IgG1 (N434A) N434A |
Single-point FcRn-enhanced | ★★★☆☆ | Single-point mutation providing a moderate 1.5–2× PK boost with low immunogenicity risk and easy manufacturing integration. |
| human IgG1 (LA) M428L / N434A |
FcRn-enhanced | ★★★★☆ | Strong PK Extension. Dual mutation combining M428L and N434A; enhances acidic FcRn binding with minimal neutral binding. |
| human IgG1 (LS) M428L / N434S |
FcRn-enhanced | ★★★★★ | Very Strong PK Extension. Extends human serum half-life up to 3–5× (>70–90 days; e.g., tixagevimab / cilgavimab). |
| human IgG1 (YTE) M252Y / S254T / T256E |
FcRn-enhanced | ★★★★★ | This Product. Benchmark PK Extension. Industry-standard benchmark delivering ~3–4× PK boost in humans (e.g., nirsevimab / Beyfortus®). |
| human IgG1 (QL) T250Q / M428L |
FcRn-enhanced | ★★★★☆ | Moderate-to-Strong PK Extension. Increases acidic FcRn affinity with favorable intellectual property freedom to operate. |
| human IgG1 (YTE + KF) M252Y/S254T/T256E + H433K/N434F |
Hyper-FcRn-enhanced / FcRn Blocker | ★★★★★ | FcRn Antagonist / Autoimmune Control. Binds tightly across pH 6.0 and 7.4 to block FcRn recycling and clear endogenous IgGs. |
| human IgG1 (V308P) V308P |
Controlled/Accelerated Clearance | ★★☆☆☆ | Tunable Fast-Clearance Variant. Modulates FcRn dissociation kinetics to yield accelerated clearance (2–5-day half-life); ideal for ADCs and immuno-PET imaging to limit non-target toxicity. |
| human IgG1 (I253A) I253A |
FcRn-null / Abrogated | ★☆☆☆☆ | Ultra-Fast Clearance Control. Complete knockout of the core FcRn binding triad; rapidly cleared within hours. |
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
- Dall’Acqua WF, Kiener PA, Wu H. Properties of human IgG1s engineered for enhanced binding to the neonatal Fc receptor (FcRn). J Biol Chem. 2006;281(33):23514-23524.
