Interference 103,781
These polyadenylation signals are typically A+T rich. In
animal cell mRNAs the consensus signal is AATAAA; variants
of this signal known to function in animal cells contain at
least five A or T residues in the six nucleotide sequence
[(Wickens, M. et al., Science, Vol. 226, pp. 1045-1051
(1984))]. In plant cells, several similar polyadenylation
signals are known; these signals contain at least four A
or T residues in the six nucleotide sequence [(Dean, C.,
et al., Nucleic Acids Research, Vol. 14, pp. 2229-2240
(1986))]. [(001088-001089)]
(6) On the last page of MDX 1478 we find teaching material
to the question of conception of Count 2. The important
paragraph reads (MDX 1478, last page, first full para.)(emphasis
added):
The B.t.k. coding sequence in pMON9711 contains many
long stretches composed solely of A and T residues. This
sequence also contains 15 copies of the sequence ATTTA
and most of the potential polyadenylation signals which
have been identified in either animal or plant cell mRNAs.
Based on this analysis, we suggest that the instability
of B.t.k. mRNA in plant cells is a function of its high
A+T content; this might be due to overall A+T composition
or the presence of specific A+T rich signals or both.
We also predict that changing the base composition of
the B.t.k. coding sequence to a lower A+T content and/or
removal of specific oligonucleotide signals rich in A+T
will lead to a significant increase in stable B.t.k. mRNA
in plant cells.
(7) Finally, on the last page of MDX 1478, we find described
alternative methods and/or approaches for altering the base
composition of the B.t.k. gene. One approach is site-directed
mutagenesis “designed to change individual nucleotides or groups
of nucleotides but would not alter the amino acid sequence of the
protein produced” (MDX 1478, last page, third full paragraph).
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