msachs at uiuc.edu
Tue Oct 13 17:59:09 EST 1998
This is actually a fairly well known phenomenon in plants. Look up the
many papers by A.G. Hunt on this subject; e.g.,
Hunt, A.G. (1994) Messenger RNA 3'-end formation in plants. Annu Rev.
Plant Physiol. Plant Mol. Biol. 45, 47-60.
Another paper to look at is:
Sachs, M.M., E.S. Dennis, W.L. Gerlach and W.J. Peacock. (1986) Two
alleles of maize Alcohol dehydrogenase 1 have 3' structural and poly(A)
addition polymorphisms. Genetics 113, 449-467.
In article <3622A6C2.CDEE3825 at med.unc.edu>, gyang at MED.UNC.EDU (Gen Yan
> David L. Haviland, Ph.D. wrote:
> > At 16:49 10/10/98 -0700, Hope of Laboratory wrote:
> > >Dear all,
> > >
> > > I would like to ask the questions about the gene structure at 3'
> > >untranslated region. I have cloned the plant cDNA with poly A tail.
> > >I can't find the polyadenylation signal (AATAA or AATAAT) at the 3'
> > >untranslated region. Is this possible or common in any gene that is
> > >the signal? Is there any alternate polyadenylation signal other than AATAA
> > >available? Is there any good and updated reference that have mentioned
> > >about polyadenylation signal [extra: and signal sequence for protein
> > >export?] ?
> > Hi:
> > Having dealt with this myself, I can tell you that one way to resove this
> > is to sequence the gene. We too had a cDNA without the polyadenylation
> > concensus sequence and long before we entertained the possibility of an
> > atypical sequence, we looked further 3'. We found it about 300 bp
> > downstream. It turns out that some poly A regions are actually within the
> > gene and serve as a place for the oligo dT to set down 5' to the real poly
> > A region.
> > Hope this helps,
> > David
> The gene I studied has two transcripts(7.4kb & 2.3kb). When I use the
> Marathon ready cDNA kit(Clontech)to do 3'-RACE, I find there is no
> Poly(A) adding signal upstream of the poly(A) tail of small transcript.
> Because the 3'-UTR of 2.3kb(170bp) is completely contained within the
> 3'-UTR(35OObp)of 7.4kb, it is not the situation that there is a poly A
> region within this gene.
> Previous work using RNase protection assay(RPA) indicated the end of
> 2.3kb mRNA lied 250bp downstream of the above-mentioned poly(A) tail.
> I do not know which end is correct. So I plan to use a fragment between
> this two position as a probe to do northern blot.If it gives two bands,
> then the end of RPA is correct.(one band is 2.3kb mRNA, the other band
> is 7.4kb mRNA). However, it is still hard to explain why there is
> poly(A) tail before this end?
> Any suggestion or explaination to this experiment will be greatly
> Thanks in advance!
> PS. The poly(A) adding signal( The later, the stronger)
> also get a cDNA without Poly(A)+ signal upstream of the poly(A) tail.
> The 3'-UTR in 2.3kb
> is contained within 3'UTR of 7.4kb
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