Multiple Reading Frames in DNA

David B. Hedrick davidbhedrick at icx.net
Sat Apr 12 12:43:50 EST 1997


Tim Taylor wrote:
> 
> Hi,
> 
> As a non-biologist, I have a small question which I hope someone
> can give me a quick answer to.
> 
> I'm sure I've read in the dim and distant past that the DNA of
> some organisms includes sections which are transcribed multiple
> times starting from different bases (different reading frames).
> These therefore get translated into completely different
> proteins, so the genome is encoding multiple messages in the
> same bit of DNA.
> 
> Can someone tell me what this phenomenon is called (if it has a
> special name), and give me an example (with a reference to a
> book, paper etc. if at all possible)?
> 
> Thanks in advance,
> 
> Tim
> 
> --------------------------------------------------------------------------
> Tim Taylor, Department of Artificial Intelligence, University of
> Edinburgh
>             tel (+44)-131-650-3081 or -650-4493  fax -650-6899
>                 web http://www.dai.ed.ac.uk/students/timt/


Hello, Tim:

	You got it - "multiple reading frames".  

	Remember that the 2 strands of DNA are anti-parallel.  If one strand is
read from left to right, the other is read from right to left.  Some
genes in eukaryotes (multi-cellular critters like us) can give different
products by being transcribed beginning at different starting points or
by terminating transcription at different points.  The really
mind-blowing example comes from viruses.  Since the selection pressure
on them is very great to reduce the size of their genome, viruses often
code for 2 different proteins on the same section of DNA!  One from each
of the 2 strands.  To see how complex this is, imagine that you wrote me
a note that gave one message, and another different message when looked
at in a mirror.  
	Any textbook in molecular biology should give you several examples.  
-- 
		~DBH

Technical writing, literature search, and data analysis at the interface
of chemistry and biology. 

	davidbhedrick at icx.com

	David B. Hedrick
	P.O. Box 16082
	Knoxville, TN 37996



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