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Unformatted text preview: D. Base pairing interactions important for spliceosome assembly and function. E. Note similarity between splicing mechanisms of pre-mRNAs and the group II self-splicing introns! RNAs in the splicing snRNPs likely evolved from intronic sequences; remnant of the ‘RNA world’ Lecture 16 MCB 161 S. Harmer 2/25/2010 • U1 binds 5’ splice junction (RNA/RNA basepairing) • U2 binds to branch site • U4/U6 (basepaired to each other) and U5 bind • Progressive rearrangements: • U1 and U4 leave (requires helicase) • U5 binds both exons • U6 basepairs with U2 to form the active site • U6/U2 catalyze first transesterification reaction (lariat intermediate formed) • U6/U2 catalyze second transesterification (exons spliced) • U2/U5/U6 leave, with lariat intron • Lariat is degraded, but U2/U5/U6 dissociate and act in another splicing reaction Steps of the spliceosome-mediated splicing reaction: Fig. 13.8...
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This note was uploaded on 03/02/2010 for the course MCB 161 taught by Professor Stacey during the Winter '10 term at UC Davis.
- Winter '10