A heavy chain is the large polypeptide subunit of a protein complex, such as a motor protein (e.g. myosin, kinesin, or dynein) or antibody (or immunoglobulin).
It commonly refers to the immunoglobulin heavy chain. The heavy (H) chain is the larger of the two types of chains that comprise a normal immunoglobulin or antibody molecule. The heavy chain portion of an antibody contains 2 regions; the Fab (Antigen-binding portion) and Fc (Constant region; confers biological activity such as phagocytosis of microorganisms, lysis, and clumping of organisms together). Amino Acid sequence determines the type of heavy chains and heavy chains define the isotype of Ig. Immunoglobulin G has gamma heavy chains, IgA has α alpha heavy chains, IgM has μ mu heavy chains, IgD has δ delta heavy chains, and IgE has ε epsilon heavy chains. In contrast, all light chains are either κ kappa or λ lambda light chains, either of which may be found on any Ig molecule, regardless of isotype. Each Ig unit is made up of 2 heavy chains, 2 light chains, and has 2 antigen-binding sites. Heavy Chain is joined with the light chain with the help of di-sulphur bonds.
Famous quotes containing the words heavy and/or chain:
“I wish you would moderate that fondness you have for your children. I do not mean you should abate any part of your care, or not do your duty to them in its utmost extent, but I would have you early prepare yourself for disappointments, which are heavy in proportion to their being surprising.”
—Mary Wortley, Lady Montagu (1689–1762)
“The years seemed to stretch before her like the land: spring, summer, autumn, winter, spring; always the same patient fields, the patient little trees, the patient lives; always the same yearning; the same pulling at the chain—until the instinct to live had torn itself and bled and weakened for the last time, until the chain secured a dead woman, who might cautiously be released.”
—Willa Cather (1873–1947)