Antibody variation

In one category of immune cells – the B cells – the variable region of the light chain gene has 40 variable (V) and five joining (J) segments. An enzyme called DNA-recombinase cuts most of these segments out of the gene, and then connecting one V segment to one J segment. This random cutting and connecting process is called splicing. After RNA processing, all but one V and J segment are spliced out. As a result, each differentiated B cell in the human body typically has a unique variable chain. The constant chain, which is not involved in binding, will be the same for all antibodies.

The table below shows the structure of the five different classes of antibodies.