heavy chain heav·y chain (hěv'ē)
One of a pair of polypeptide chains of high molecular weight that are components of an immunoglobin and that serve as the binding sites for antigens. They are separated into five types: gamma, alpha, delta, epsilon, and mu.
The larger of the two types of polypeptide chains in an immunoglobulin molecule. A heavy chain consists of an antigen-binding portion having a variable amino acid sequence, and a constant region that is different for each class of imunoglobulin. Each heavy chain is one of a Y-shaped identical pair and is attached along its variable region to a smaller light chain. Compare light chain.