introns-exons starts and ends.

Richard P. Grant r_grant at see.sig.for.address
Wed Aug 25 11:10:39 EST 1999

In article <7pvcdi$hks at net.bio.net>, Brice Quenoville
<quenovib at naos.si.edu> wrote:

>1/Is the so called GT-AG rule stating that all eukaryotic
>nuclear introns begin with a GT and finish with a AG
>believed to be that universal or not? 

'Nearly always true' I think is the closest . . .  :))

>and AG always be excised when going to cDNA or can they (or
>part of them) be part of it? 

The GU . . . AG is part of the intron and so is excised.

>2/Is it possible that, searching for a reading frame, a
>codon triplet would begin at the end of one exon and finish
>at the beginning of the next or is each exon a complete
>succession of codons (I would guess so but)?

You'd think so, wouldn't you?  No, the intron boundary frequently occurs
in the middle of a triplet.  At least in fibronectin, anyway :-)  I guess
you've a one in three chance of getting a complete IN REGISTER triplet at
any given splice point.



Richard P. Grant MA DPhil     |             rgrant at cmtech.co.uk
work: www.cmtech.co.uk        |      home: www.avnet.co.uk/adastra
 -- 'Rule 6:  There is nooooooooooooooooooooaaaawwwwww Rule 6' --

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