Antibody production is a response to foreign molecules invading the body. Antibodies exist as one or more Y-shaped monomers consisting of four polypeptide chains. Each Y-shaped monomer contains two identical heavy chains and two identical light chains, which differ in sequence and length. The top of the Y-shaped monomer contains a variable region that can specifically bind tightly to an epitope on an antigen. The light chains of antibodies can be classified as either kappa (κ) or lambda (λ) types based on minor differences in their polypeptide sequences.
