Figure 1.

Overview of the splicing reaction. The pre-mRNA must contain at least two exons (boxes) interleaved by one intron (black line) to be relevant for splicing. A single intron is defined by a pair of 5’- and 3’-splice sites (5ʹss, 3ʹss), as well as the branch point (BP) adenosine. Five small nuclear ribonucleoproteins (snRNPs) are the core components of the spliceosome machinery (U1/2/4/5/6) which requires auxiliary factors such as SF1 and U2AF. For each step in the diagram, the name of the corresponding spliceosomal complex is given.