RNA Splicing . Prokaryotic genes : the codon is immediately adjacent to another Eukaryotic genes : consists of blocks of coding sequences separated by noncoding sequences Thus! RNA splicing is necessary to eliminated these noncoding sequences. outline. The chemistry of RNA splicing
: since the translation is conducted in a fixed frame, even one base lost or insertion would result in the change of the reading frame, which would further result in error protein…
A. 3’ splice site:
B. 5’ splice site
C. branch point site
2’ OH of A at branch site as nucelophile to attack the phosphoryl group of G in the 5’ splice site
phosphodiester bond cleavage between intron and exon at 5’ splice site
5’ exon and 3’ exon are spliced ; intron lariat is released
U1 attached to 5’ splice site
BBP binds to A within branch site
U2AF binds to Py tract
U2 binds to branch site aided by U2AF to replace BBP
A residue extruded as bulge resulting form the base pair between U2 and branch site
form only one gene.
2. regulating the use of intron, which, if retained in the mRNA, the latter would never be transported outside the nucleus thus would never be translated.