Based on differences in the amino acid sequences in the constant region of the heavy chains there are
five classes of Igs.
1. IgG- gamma heavy chain
2. IgM-miu heavy chain
3. IgA- alpha heavy chain
4. IgD- delta heavy chain
5. IgE- epsilon heavy chain.
In each class of Ig small differences in the constant regions of the heavy chain still occur, leading to
subclasses of the Igs e.g. IgG1,IgG2,IgG3 etc.