Polyadenylation signal

David L. Haviland, Ph.D. dhavilan at IMM2.IMM.UTH.TMC.EDU
Mon Oct 12 09:46:04 EST 1998

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. However
>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 absence
>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?]  ?


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 L. Haviland, Ph.D.
 Asst. Prof. Immunology 
 University of Texas - Houston, H.S.C.
 Institute of Molecular Medicine  
 2121 W. Holcombe Blvd.  
 Houston, TX  77030 
 Internet:"dhavilan at imm2.imm.uth.tmc.edu" 
 Voice: 713.500.2413  FAX: 713.500.2424
Never take life seriously. Nobody gets out alive anyway.

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