Structure and assembly of the spliceosomal snRNPs

The spliceosome is a macromolecular machine that carries out the excision o f introns from eukaryotic pre-mRNAs and splicing together of exons. Four la rge RNA-protein complexes, called the U1, U2, U4/U6 and U5 small nuclear ri bonucleoprotein particles (snRNPs), and some non-snRNf proteins assemble ar ound three short conserved sequences within the intron in an ordered manner to form the active spliceosome. We aim to provide insight into the molecul ar details of the mechanism of pre-mRNA splicing through crystallographic s tudies of the snRNPs. We have solved the X-ray crystal structure of some sn RNP proteins as part of either protein-protein complexes or RNA-protein com plexes. These structures have provided an important insight into the overal l architecture of the U1 and U2 snRNPs and the mechanisms of RNA-protein an d protein-protein recognition.