V Regions Through DNA Splicing -
Splicing and rearrangement of DNA sequences take place in antibody producing cells to create a large variety of Ig genes. As an example, we will discuss DNA splicing only for the heavy chain. There are two rearrangements in this case:

(a) the first generating the DNA sequence coding for VH and

(b) the second leading to association of a specific VH with a definite CH sequence.

Using molecular probes in different kinds of cells, steps involved in rearrangements leading to association of different V regions could be worked out. In IgM sequence, it is shown that in embryo or germline cells, V Hand CH regions have a small region of J sequence. Between V and J sequences, presence of D sequence was also shown.

Although there is diversity in V, J and D sequences (C region is constant), but variation is also provided by the manner in which DNA splicing and rearrangement, is brought about.