Unformatted text preview: nuclear genes are
unique in that they share short, highly conserved sequences (GU/AG) in the
junctions between the exon and intron. Splicing is said to obey the GU/AG rule.
GU/AG Intron 1
5’ Exon1 3’
A64G73/G100U100A62A68G84U63 (Py Stretch)-18-40nt-A100G100/N Exon2 Branch point
Py80 N Py80 Py87 Pu75 A100 Py95
Py Subscripts = % occurrence
Py = pyrimidine; Pu = purine; N = any nucleotide; nt = nucleotides
BIS101001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013
BIS101001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez 29 Splicing Introns from Eukaryotic mRNA
The discovery that eukaryotic genes were interrupted by intervening DNA
sequences (introns) iimmediately raised the question of how they would
be removed (spliced out).
This is necessary if the mRNA is to be colinear with the protein it
It is now known that RNA splicing involves the precise cleavage of
phosphodiester bonds at the exon-intron boundarie...
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