MBB 222 Lecture Notes - Lecture 30: Guanosine Monophosphate, Phosphodiester Bond, Spliceosome
20 Dec 2018
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Document Summary
Proposed mechanism for bringing the 5" and 3" splice sites together splicing occurs during transcription. Must bring the 5" and 3" splice sites together to ligate the upstream and downstream exons once the intron lariat is released spliceosome components associate with the c- terminal domain (ctd) of rna polymerase ii. As the first splice junction (the 5" splice site) of the mrna is synthesized, it is bound by. After splicing, the intron is degraded in the nucleus by nucleases. Self-splicing group i and ii introns splicing requires no protein. Both group i and group ii introns are self-splicing ribozymes (spliceosome- independent). No spliceosome is involved - instead, the intron itself serves as the enzyme that catalyzes splicing - a ribozyme. No lariat structure is formed (no branch site used), intron is degraded by nucleases. Group ii introns also catalyze their own splicing reaction reaction is very similar to that of spliceosome-mediated splicing.
