| Modification Notes |
Antibody producing cells of the immune system require multiple rearrangements of immunoglobulin (Ig) genes. Immunoglobulins are four-chain, Y-shaped, monomeric structures of two identical heavy chains and two identical light chains held together through interchain disulfide bonds. Immunoglobulins in vertebrates help to remove non-self molecules or cells (antigens) by recognizing and binding to the antigen and carrying out effector functions that activate the immune system. Variable genetic combinations of the five heavy chain classes (M, D, G, E and A) and the two light chain isotypes, ˚ and ¬, confer the role of an antibody. The variable region genes encoding immunoglobulin ˚ and ¬ chains are assembled from three DNA segments, the V, C and J genes. Human ˚ light chain genes map to chromosome 2 and the human ¬ light chain genes map to chromosome 22. ˚ gene recombination can precede ¬ gene recombination during B cell ontogeny and only a single light chain type is expressed in individual B cells. Antibodies in camels and sharks can lack light chain, suggesting that light chain may not be essential for antigen binding in some vertebrates. Ig ¬ Chain V4A is a 117 amino acid immunoglobulin region encoded by the IGLV7-43 gene. |
