VMC 221: Veterinary Immunology and Serology (1+1)

LIGHT CHAINS

• Two light chains are either κ (Kappa) or λ (lambda) but never both in one immunoglobulin.
• The names were derived from Koragold (κ) and Lapori (λ) who originally described. Each light chain consists of two domains of 110 amino acids.
• The amino acid sequence of C-terminus domain is constant (C_L) where as sequence of N-terminus is variable (V_L) and some regions show great variability, known as hyper variable regions or complementarity determining regions (CDRs) or hot spots, each containing 6-10 amino acids. Between the CDRs there are intervening peptide sequences called frame work regions.
• Three regions show maximum variability i.e. at position 24-34, 50 to 56 and 89-97.
• The amino acid sequence in V_L domain of each light chain is different. Molecular weight of each light chain is 25KDa.
• The presence of κ or λ light chain varies with species. For example, cattle and horses have 95 % λ, rat and mice have over 95 % κ chain, monkeys have 50 % of each and humans have 60 % κ chains.