Semantic resources project/Antibodies/Preliminary work/List of immunoglobulin isotypes

Immunoglobulin isotypes: the genetic variations or differences in the constant region of the heavy chain of the Ig (immunoglobulins) classes and sub-classes (from Wikipedia).

A typical antibody is composed of two immunoglobulin (Ig) heavy chains and two Ig light chains.

There are five types of mammalian immunoglobulin heavy chain:


 * α defines class of immunoglobulin: IgA 1, 2
 * δ defines class of immunoglobulin: IgD
 * γ defines class of immunoglobulin: IgG 1, 2, 3, 4
 * ε defines class of immunoglobulin: IgE
 * μ defines class of immunoglobulin: IgM - The IgM molecule is mostly a pentamer but can be a hexamer

There are two types of light chain in mammals,
 * lambda (λ) chain
 * kappa (κ) chain

Classes of immunoglobulin:

IgA
It exists in two isotypes, IgA1 (90%) and IgA2 (10%). It can exist in a dimeric form called secretory IgA (sIgA). Polymeric? The major polymeric form is the IgA dimer, which contains a single J chain joined to two IgA monomeric subunits. Trimers and higher polymeric forms exist in

IgG
Monomer (2 identical heavy chains α, 2 identical light chains -> tetrameric quaternary structure). The two heavy chains are linked to each other and to a light chain each by disulfide bonds. The resulting tetramer has two identical halves which together form the Y-like shape. Each end of the fork contains an identical antigen binding site. Found also IgG2a, IgG2b