1. Chapter 14
RNA Processing I : Splicing

2. Summary of splicing
Transcription
Primary transcript
 splicing
mature transcript
Evidences for introns
R-loop in the electron microsopic view of chromatin
sequencing ; compare genomic DNA and cDNA

3. Splicing signals and mechanism
Lariat structure
Introns almost all start with GU and end with AG
Branch point
Spliceosome ; pre-mRNA,
snRNPs (snurps); protein
RNA ; U1,2,4,5,6

4. Spliceosomal pre-mRNAU2 U5 U6

5. The spliceosome cycle
Model for participation of CTD in exon definition
- The CTD acts as a platform for the gathering of pre mRNA and splicing factors.

6. Alternative splicing
Ex) Mu RNA; secreted form and membrane-bound form
Sex determination in Drosophila ; 8 chromosomes (X/Y, 2, 3, 4 autosomes)
male = XY female= XX
Sxl activates tra activates dsx to determine female.

7. Self-splicing RNAs Group I intron Group II intron
serendipity
Self-splicing RNAs
Group I intron
Group II intron
Thomas Cech ;
Nobel prize 1989
Any possibility of contamination of spliceosome in the in vitro transcription?  chemically synthesize the precursor  splicing still occurs
Tetrahymena
(ciliate)

8. Group I intron
GTP

9. Spliceosomal pre-mRNA
Group II intron U2 U5 U6
Group II intron’s splicing mechanism is similar to pre mRNA’s splicing
- They have A at the branch point.

10. Phe 5’ Is self-splicing RNA true enzyme? Catalytic RNA = Ribozyme
M1 RNA of RNase PI
Telomerase
CoTc 5’
RNaseP