Final answer:
The Ig light chain consists of 214 amino acids, divided into a variable (VL) region and a constant (CL) region, which together with the heavy chain forms the Y-shaped structure of immunoglobulins. The light chain also contains intrachain disulfide bonds creating domains critical for antibody function and antigen recognition.
Step-by-step explanation:
The gene structure of immunoglobulin (Ig) light chains is integral to the function and variability of antibodies. Light chains come in two types, kappa (κ) and lambda (λ), each consisting of a variable (Vκ or Vλ) and a constant (Cκ or Cλ) region. The light chain protein of the kappa type is made up of 214 amino acids with the variable light (VL) region spanning from amino acid 1 to 108 and the constant light (CL) region from 109 to 214. The variability in the light chain is primarily in the VL region, where specific segments are designated as hypervariable regions or complementarity determining regions (CDRs) that determine the specific antigen binding properties.
In the immunoglobulin structure, the light chains pair with heavy chains to form a basic Y-shaped structure. Each light chain contains two intrachain disulfide bonds, creating two domains: one in the VL and one in the CL region. Similarly, the heavy chain contains four intrachain disulfide bonds, resulting in four domains. The entire Ig molecule is held together as a tetramer (L2H2) by interchain disulfide bonds, and its flexibility is facilitated by a region between certain domains of the heavy chain. Upon enzymatic digestion, fragments produced include two antigen-binding fragments (Fab) and one crystallizable fragment (Fc).