The U5 and U6 Small Nuclear RNAs as Active Site Components of the Spliceosome

• DOI: 10.1126/science.8266094
• Publication Date: 2006-10-05T23:05:09Z
• Authors: Erik J. Sontheimer; Joan A. Steitz
• Keywords: Spliceosome; Protein splicing; Post-transcriptional modification; Small nuclear RNA; Precursor mRNA

Five small nuclear RNAs (U1, U2, U4, U5, and U6) participate in precursor messenger RNA (pre-mRNA) splicing. To probe their interactions within the active center of mammalian spliceosome, substrates containing a single photoactivatable 4-thiouridine residue adjacent to either splice site were synthesized, crosslinks induced during course vitro An invariant loop sequence U5 contacts exon 1 before after first step splicing because crosslink between last appeared pre-mRNA then cutoff intermediate. Both these crosslinked species could undergo subsequent splicing, indicating that reflect functional interaction is maintained through both reaction steps. The same aligns two exons for ligation since 2 also became lariat U6 conserved second position intron intermediate product. On basis results, several conformational arrangements spliceosomal can be distinguished, additional mechanistic parallels spliceosome self-splicing introns drawn.