Antibodies, also known as immunoglobulins (Ig), are specialized proteins produced by the immune system. Each antibody consists of four polypeptide chains: two heavy chains and two light chains, forming a characteristic "Y"-shaped structure.
Figure 1. A schematic diagram of an IgG1 showing the various components of the heavy (H) and light (L) chains.
Variable and Constant Regions
The variable region, located at the tips of the Y-shaped antibody, determines the antibody's specificity for antigen binding. This region consists of 110–130 amino acids and includes both the light chain (L-chain) and heavy chain (H-chain) termini.
Proteolytic cleavage of an antibody using specific proteases can separate this region, generating Fab fragments (fragment antigen binding), which retain antigen-binding properties.
The constant region defines the antibody's biological function and determines how the immune system responds to the bound antigen. Based on differences in the constant region, antibodies are classified into five major isotypes: IgM, IgG, IgA, IgD, and IgE, each playing distinct immune roles.
Figure 4. The polymeric structure of different types of immunoglobulins.
L-Chain
- • light chain (L-chain) consists of approximately 220 amino acids
- • The first 100–110 amino acids at the N-terminal vary among antibodies, forming the variable (V) region responsible for antigen binding.
- • The remaining 110 amino acids at the C-terminal form the constant (C) region, which can be either Lambda (λ) or Kappa (κ).
H-Chain
- • The first 110 amino acids at the N-terminal show significant variability among antibodies, forming the variable (V) region.
- • The remaining portion of the H-chain is more conserved, forming the constant (C) region, which differs among antibody isotypes.
Fab and Fc Regions
- • The Fab region is responsible for antigen binding, while the Fc region interacts with immune system components, such as phagocytic cells and complement proteins.
Why Choose Abinscience for Antibody Solutions?
At Abinscience, we provide high-quality monoclonal and polyclonal antibodies tailored for immunology, oncology, and infectious disease research. Our antibody catalog includes validated products optimized for ELISA, Western blot (WB), immunohistochemistry (IHC), and flow cytometry (FCM).
Popular Antibody Products from Abinscience:
References:
[1] Krishna T C, Najda A, Bains A, et al. Influence of ultra-heat treatment on properties of milk proteins[J]. Polymers, 2021, 13(18): 3164.
[2] O. Acheampong D, K. Adokoh C, Ampomah P, et al. Bispecific antibodies (bsAbs): promising immunotherapeutic agents for cancer therapy[J]. Protein and peptide letters, 2017, 24(5): 456-465.
