In article <354nir$rsp at mserv1.dl.ac.uk>
"Peter Hare" <HARE at gate2.cc.unp.ac.za> writes:
>>Could anyone refer me to any reports of variable sites of
>addition of a poly(A) tail from a single polyadenylation signal?
>>I have recently sequenced the 3' end of an Arabidopsis cDNA, the
>sequence of which has already been published. The cDNA I have
>sequenced has been truncated 7 bp before the sequence published.
>In both cases the same polyadenylation signal appears to have
>been used. The rest of the 3' untranslated region is identical in
>both cDNAs. The two poly(A) tails differ in length by only a
>>Is this a common occurrence in transcription of plant genes? None
>of the reviews of mRNA 3' formation I have seen mention such a
>phenomenon. I would also greatly appreciate any input regarding
>how this apparently anomalous situation may have arisen.
>>Dept. of Botany
>University of Natal
>hare at botany.unp.ac.za
What you have described (multiple polyadenylation sites in a plant
transcription unit) is quite the norm in plant genes. There may be more, but
I am aware of only two cases where a single poly(A) site is used.
The situation you describe (two sites 7 nts apart) might be due to different
poly(A) signals, but is more likely due to the use of different cleavage/
It is easy to think of this as anomolous if one thinks like a mammal, but
this situation is really the norm in all other organisms (it has been reported
in yeast, and is not unlike how rho-dependent termination sites look in E.
Arthur G. Hunt
Department of Agronomy
University of Kentucky
Lexington, KY 40546-0091 USA
Tel: (606) 257-3637
Fax: (606) 323-1952
email: aghunt00 at ukcc.uky.edu