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:
“O kinsmen of the Three in One,
O kinsmen, bless the hands that play.
The notes they waken shall live on
When all this heavy history’s done;
Our hands, our hands must ebb away.”
—William Butler Yeats (1865–1939)
“The name of the town isn’t important. It’s the one that’s just twenty-eight minutes from the big city. Twenty-three if you catch the morning express. It’s on a river and it’s got houses and stores and churches. And a main street. Nothing fancy like Broadway or Market, just plain Broadway. Drug, dry good, shoes. Those horrible little chain stores that breed like rabbits.”
—Joseph L. Mankiewicz (1909–1993)