In most eukaryotic genes the information (or code) in the DNA sequence is interrupted by non-coding regions called "introns". An RNA copy of the gene has to be cut and then spliced back together to remove the introns and produce a continuous "message" with the correct information to produce a protein (see powerpoint presentation below: "What is RNA splicing?"). In many cases, the message can be cut and put back together in different combinations giving rise to proteins with different functions. This means that the number of different proteins in a cell can be much greater than the number of different genes. Mistakes in the splicing of the RNA cause serious problems as defective proteins are produced, and this sometimes happens as a consequence of genetic defects or disease. The splicing machinery is highly complex and must be tightly regulated. We aim to understand how the many components assemble to form a functional machine and how its activity is controlled. The RNA splicing machinery is highly conserved between yeast and humans. We use yeast as a model organism as many powerful experimental techniques are available and it can provide important insights into splicing in humans