| Modification Notes |
Immunoglobulin (Ig) and T cell receptors of B and T lymphocytes are encoded in multiple germ line DNA segments known as V, D and J, that are rearranged during lymphocyte development. V(D)J recombination is a site specific recombination event in vertebrate genes. The assembly of antigen receptor genes by V(D)J recombination is initiated by a recombination activator genes 1 and 2 (RAG1/RAG2) protein complex, which introduces double-strand breaks between recombination signal sequences and their coding DNA. The RAG-1 and RAG-2 were originally identified on the basis of their ability to activate rearrangement of an exogenous recombinational substrate in fibroblasts; moreover, both genes are required for this activity. RAG1 and RAG2 proteins catalyze V(D)J are essential for generation of the diverse repertoire of antigen receptor genes and effective immune responses. RAG2 is composed of a "core" domain that is required for the recombination reaction and a C-terminal nonessential or "non-core" region. Activated mature CD5-positive human tonsil B cells coexpress both RAG1 and RAG2 mRNA and protein, and display DNA cleavage resulting from their recombinase activity. |