The<unk>  <unk>  is the large polypeptide subunit of an antibody (immunoglobulin).
A typical antibody is composed of two immunoglobulin (Ig)<unk>  chains and two Ig light chains. Several different types of<unk>  chain exist that define the class or isotype of an antibody. These<unk>  chain types vary between different animals.  All<unk>  chains contain a series of immunoglobulin domains, usually with one variable domain (VH) that is important for binding antigen and several constant domains (CH1, CH2, etc.).
Immunoglobulin heavy chain
Immunoglobulin A
Light chain
Immunoglobulin M
Immune complex
Immunoglobulin E
Immunoglobulin G
Antibodies