Plasmid Name
pHCIgG1LA(M428L/N434A)
Mutation Set
M428L + N434A
Selection Marker
Ampicillin
Promoter
CMV
Fc Engineering Overview
The Human IgG1 (LA: M428L/N434A) Fc variant introduces two synergistic mutations within the CH3 domain designed to enhance FcRn binding affinity at acidic pH. This modification delivers robust serum half-life extension (1.5–3×) and a long-acting PK profile while preserving normal FcγR interactions, C1q binding, and effector functions (ADCC/CDC).
Functional Profile
| Property | Effect |
|---|---|
| FcγR binding | Normal |
| ADCC | Normal |
| CDC | Normal |
| FcRn binding | Increased ↑↑↑ |
| Serum half-life | Extended ↑↑↑ |
| PK profile | Long-acting |
| Effector potency | Normal |
Mechanism of Action
The LA Fc variant introduces two synergistic mutations—M428L and N434A—within the CH3 domain of IgG1. These mutations enhance the affinity of the Fc region for FcRn at acidic pH, improving recycling and reducing lysosomal degradation. Unlike YTE, LA maintains near-normal FcγR and C1q interactions, making it a half-life extension module with minimal impact on effector function.
Phenotypic Effects
- Increased FcRn binding affinity.
- Extended serum half-life (1.5–3× depending on species).
- Maintains normal ADCC and CDC.
- Preserves structural integrity and antigen binding.
- Ideal for long-acting therapeutic antibodies.
Applications
- Long-acting therapeutic antibodies.
- FcRn mechanistic studies.
- PK/PD optimization.
- Antibodies requiring preserved effector function.
- Preclinical development of extended-duration biologics.
Plasmid Map & Feature Annotation
Insert Structure: VH – CH1 – hinge – CH2 – CH3(M428L/N434A)
- VH: Variable heavy domain
- CH1: Constant heavy 1
- Hinge: Native IgG1 hinge
- CH2: Constant heavy 2
- CH3(M428L/N434A): FcRn-enhancing mutations
Product Note: The LA Fc variant is widely used in next-generation long-acting biologics. It provides robust half-life extension while preserving effector function, making it a versatile engineering module for therapeutic antibodies.
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 | ★★★★☆ | This Product. 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 | ★★★★★ | 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
- Yeung YA et al. Engineering human IgG1 affinity to human neonatal Fc receptor: impact of affinity improvement on pharmacokinetics in primates. J Immunol. 2009;182:7663–7671.