🚀 go-pugleaf

toms@kaylor.ncifcrf.gov (Tom Schneider) wrote:

>Ken Muldrew (kmuldrew@acs.ucalgary.ca) wrote:

>: The information as to where to
>: cut and splice these sequences has to be coded somewhere and the
>: introns just happen to be at the right place at the right time. Since
>: RNA is single stranded, it can (and probably does) fold in on itself
>: to form hydrogen bonds. The introns probably contain sequences which
>: allow for specific tertiary structures to form which are then
>: recognized by splicing proteins (look at a picture of a tRNA to get an
>: idea of what I'm talking about here).

>Although you are right that there are structures, I think that the majority
>of the sequence conservation for locating the boundaries between introns
>and exons is simple pattern in the sequence.  See:

>  http://www-lmmb.ncifcrf.gov/~toms/paper/splice

>(especially pages 31 and 32) for a detailed information analysis.

Since I had Kornberg (DNA Replication, 2nd ed.) down from the shelf, I
couldn't resist a little browsing. It turns out that T4 phage (a phage
is a virus that infects bacteria) has introns in its genome. Since
prokaryotes have no mechanism for slicing introns out of the primary
RNA transcript, it is thought that the tertiary structure of the RNA
provides the information necessary  for either self-excision or
skipping during translation. Ya' gotta love it.
Ken Muldrew
kmuldrew@acs.ucalgary.ca