Article Abstract:
A site-specific recombination reaction, known as V(D)j recombination, is responsible for assembling immunoglobulin and T-cell-receptor genes from gene segments. Recombination-activating genes, RAG1 and RAG2, encode proteins that are essential in this process. They are found in all jawed vertebrates but not in jawless vertebrates, suggesting that split antigen receptor genes arose with the divergence of bony and cartilaginous fish. New research shows that the repertoire of immunoglobins and T-cell receptors is owed to a single transposon insertion occurring some 450 million years ago.
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Article Abstract:
The recent discovery of the CD40 ligand and the role of the CD40 receptor-CD40 ligand interaction in B-cell activity has led to the identification of CD40 ligand gene mutations as cause of the immunodeficiency disease HIGM1. T-cells must contact B-cells to activate antigen memory in B-cells, to enable B-cells to proliferate and to enable the B-cells to produce appropriate isotypes of immunoglobulin. The defective CD40 ligand genes do not produce a ligand that facilitates the activation of memory or isotype switching in B-cells, and this is apparently responsible for HIGM1.
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Article Abstract:
The gene that controls development of X-linked agammaglobulinemia (XLA) also produces a newly discovered protein-tyrosine kinase. XLA, a rare genetic disorder affecting boys, results from the failure of B lymphocytes to grow and is characterized by vulnerability to infections due to a weakened antibody response. David Vetrie and colleagues found that the agammaglobulinemia protein-tyrosine kinase (Atk) is encoded by the same gene that produces XLA. This finding may lead to further biochemical research concerning XLA.
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