Immunoglobulin G (IgG), a widely expressed serum antibody, has two heavy chains and two light chains connected by a disulfide bond. It is a glycoprotein, usually found as a monomer. IgG is further subdivided into four classes namely, IgG1, IgG2, IgG3, and IgG4. IgG antibody subtype is the most abundant of serum immunoglobulins of the immune system. About 70 % of the total immunoglobulin consists of IgG.
