Macromolecules with common structural and functional features, such as the IgG, IgM, IgA, IgD, and IgE antibody isotypes.
Isotypes refer to the classes of immunoglobulins IgG, IgA,IgM, IgD, and IgE which have similar structures but differ in molecular weight and concentration in the blood.
Antigenic determinants of immunoglobulin heavy chains that define classes of immunoglobulins, such as IgM and IgE, and subclasses, such as IgG1 and IgG2.
Classes of antibody that differ in the constant region of their heavy chain (Fc portion); distinguishable also on the basis of reaction with antisera raised in another species. These differences also result in different biological activities of the antibodies.
Immunoglobulins are made in several distinct isotypes or classes- IgM, IgG, IgD, IgA, and IgE-each of which has a distinct heavy-chain C region encoded by a distinct C-region gene. The isotype of an antibody determines the effector mechanisms that it can engage on binding antigen. The different heavy-chain C regions are encoded in exons 3' to the V(D)J rearrangement site. This allows the same antibody heavy-chain V region to link up with different heavy-chain C-region isotypes as a result of somatic recombination.
