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Unformatted text preview: bonucleoproteins (snRNPs)
Splicesosomes are assembled as their components bind to pre-mRNA
Splicesosomes consist of a variety of proteins and rinonucleoproteins (small nuclear RNAs + proteins)
snRNAs may be the catalytically active components of the snRNPs, not the proteins based on:
pre-mRNA are catalyzed by the same pair of chemical reactions in splicesosomes and group II introns
the snRNAs required for splicing pre-mRNA resemble group II introns Initiation of transcription by RNA polymerase II is associated with phosphorylation of the C terminal domain (CTD) o
o serves as scaffold
The pattern of phosphorylation changes as polymerase transcribes the gene
The initiation of transcription is associated with TFIIH-catalyzed phosphorylation of serine residues at the 5
position of each heptad repeat of the CTD (at the 5th in each group of 7)
Phosphorylation triggers the separation of transcription machinery from transcription factors and/or the
Elongation factors then become associated with the polymerase as it moves along the DNA mRNA processing- Evolution
o Which came first, protein or DNA? neither!
The idea of an RNA world suggests that RNA was the ear...
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