Abstract
In the forty years since the discovery of mRNA splicing, extensive research in the areas of biochemistry and genetics generated a basic description of the fundamental mechanisms of splicing and components of the spliceosome, the enzyme responsible for its catalysis. Recently, our understanding of the spliceosome structure was radically expanded by the publication of cryo-EM structures of several forms of this complex (the Nagai, Shi, and Lührmann labs). However, a number of important questions regarding the spliceosome function remain unresolved. Using the still cryo-EM images as illustrations, I will discuss the dynamic rearrangements of the spliceosome, impacting function of its catalytic center.