What is alternative RNA splicing?

Alternative RNA splicing occurs in eukaryotic cells, enabling eukaryotes to make multiple proteins from a single gene. Eukaryotic messenger RNA contains expressed regions called exons and intervening regions called introns. Before mature mRNA exits the nucleus, molecules of small nuclear RNA remove introns and select which exons get joined together.

The exact mechanism of alternative splicing remains an intense area of research. Although small nuclear RNA and nuclear proteins play a pivotal role, other signaling molecules are involved as well. For example, when the fibroblast growth factor receptor-1 gene is activated, the alpha isoform is transcribed if a cytokine called interferon gamma is present; however, if a cytokine called interleukin 6 is present, the beta isoform of FGFR-1 is produced.

Antibody and T-cell receptor diversity represent the ultimate examples of alternative RNA splicing. From a repertoire of barely 100 gene segments, B and T lymphocytes can mix and match these exons into 25 million novel antibodies and T-cell receptors.