light chain n.
One of a pair of polypeptide chains of low molecular weight that are components of an immunoglobin and are classified as one of two types: lambda or kappa.
The smaller of the two types of polypeptide chains in an antibody molecule. A light chain consists of an antigen-binding portion with a variable amino acid sequence, and a constant region with an amino acid sequence that is relatively unchanging. The light chains are attached to the heavy chains so that the variable regions of both lie alongside each other. Compare heavy chain.