Unformatted text preview: ht, the phosphate on the
G at the 5’ end of intron 1 forms a bond with
the 2'OH of the branch point A.
The 3'OH on the end of Exon 1 attacks the
5' end of Exon 2, to form a phosphodiester
bond. The structure of the released intron
is referred to as a lariat.
This occurs inside the nucleus and about 2
to 30 minutes after the transcript is initiated.
to A BIS101001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013
BIS101001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez A A 31 Spliceosome is a small ribonucleoprotein (Snurp)
The spliceosome is a special
called a small
ribonucleoprotein or “Snurp”.
The spliceosome contains
several small RNAs (U1, U2,
U4, U5 and U6).
These RNA molecules
complementary to the
conserved sequences in the
These RNAs range in size
from 115 bases to 189 bases
in mammals and 110 to 1175
in yeast. Some snRNAs are
very rare while others may be
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