Human lgG Antibodies

Structure of Human IgG

Human Immunoglobulin G (Human IgG) is a Y-shaped glycoprotein with a molecular weight of approximately 150 kDa. This molecular weight varies slightly among different subclasses, mainly due to changes in the amino acid sequence of the constant region and glycosylation modifications.

This protein is composed of two identical heavy chains and two identical light chains, which are connected by disulfide bonds. The "variable region" is formed by the variable domains of the light chain and the heavy chain, and constitutes the specific antigen-binding site; while the "constant region" determines its effector function, such as activating complement or binding to Fc receptors. Its unique hinge region endows the molecule with flexibility, facilitating the simultaneous binding of antigens and the mediation of downstream immune responses.

Fig. 1 Structure of Human IgG1 (1HZH), Showing Fab Flexibility Relative to Fc.¹

Key structural properties of Human IgG:

• Y-shaped tetranucleotide basic structure (two heavy chains and two light chains)
• Specific antigen binding sites are formed in the variable region located in the Fab segment
• Located in the Fc period of constant region mediated effect function
• Hinge area provide molecular conformational flexibility, connected to the Fab and Fc fragment

Functions of Human IgG

The core function of human immunoglobulin G (Human IgG) is to recognize and eliminate pathogens, and to mediate humoral immune responses. Its main physiological functions are as follows:

Unlike the rapid response of IgM, the production of IgG occurs later but lasts longer and has a higher affinity. Its concentration significantly increases during the secondary response, demonstrating the memory characteristic of adaptive immunity.

Applications of Human IgG and Human IgG Antibody in Literature

1. Vidarsson, Gestur, Gillian Dekkers, and Theo Rispens. "IgG subclasses and allotypes: from structure to effector functions." Frontiers in immunology 5 (2014): 520. https://doi.org/10.3389/fimmu.2014.00520

The article indicates that the content of IgG in human serum is the highest. The differences in the constant regions of the four subtypes (IgG1-4) result in different binding efficiencies to FcγR and C1q, which in turn affect effector functions such as phagocytosis, ADCC, and complement activation. This review will focus on how IgG polymorphisms and glycosylation modifications regulate these functions.

2. Wisnewski, Adam V., Julian Campillo Luna, and Carrie A. Redlich. "Human IgG and IgA responses to COVID-19 mRNA vaccines." PloS one 16.6 (2021): e0249499. https://doi.org/10.1371/journal.pone.0249499

This study followed up on 4 subjects and found that the COVID-19 mRNA vaccine can effectively induce serum IgG and IgA against the spike protein. The kinetics of both are similar, but IgA decreases more rapidly after vaccination, and there is a significant difference in the persistence of the serum.

3. Allhorn, Maria, et al. "Human IgG/FcγR interactions are modulated by streptococcal IgG glycan hydrolysis." PloS one 3.1 (2008): e01413. https://doi.org/10.1371/journal.pone.0001413

The article indicates that the endoglucanase EndoS of Streptococcus can hydrolyze the N-glycans of all subtypes of human IgG, disrupting their binding to Fcγ receptors and inhibiting the effector functions of antibodies. This enzyme can not only be used as a research tool, but also may be applied in the treatment of antibody-mediated pathological processes.

4. Ermert, David, et al. "The molecular basis of human IgG-mediated enhancement of C4b-binding protein recruitment to group A Streptococcus." Frontiers in Immunology 10 (2019): 1230. https://doi.org/10.3389/fimmu.2019.01230

The article indicates that Streptococcus pyogenes achieves this by dimerizing its M protein family member Protein H, which binds with high affinity to the Fc segment of human IgG, thereby recruiting the complement inhibitor C4BP, thereby inhibiting the host immune clearance and enhancing the virulence.

5. Lis-Kuberka, Jolanta, et al. "Lectin-based method for deciphering human milk IgG sialylation." Molecules 24.20 (2019): 3797. https://doi.org/10.3390/molecules24203797

The article indicates that the glycosylation pattern of maternal breast milk IgG (particularly sialylation) is different from that of maternal plasma IgG, and is influenced by factors such as the lactation stage, premature birth, and maternal infection. The lectin-ELISA analysis shows that this pattern changes dynamically along with the lactation process, suggesting its functional specificity.

Creative Biolabs: Human IgG Antibodies for Research

Creative Biolabs specializes in the production of high-quality Human IgG antibodies for research and industrial applications. Our portfolio includes monoclonal and polyclonal antibodies tailored for ELISA, Flow Cytometry, Western blot, immunohistochemistry, and other diagnostic methodologies.

• Custom Human IgG Antibody Development: Tailor-made solutions to meet specific research requirements.
• Bulk Production: Large-scale antibody manufacturing for industry partners.
• Technical Support: Expert consultation for protocol optimization and troubleshooting.
• Aliquoting Services: Conveniently sized aliquots for long-term storage and consistent experimental outcomes.

For more details on our Human IgG antibodies, custom preparations, or technical support, contact us at info@creative-biolabs.com.