VPg and its ramifications

Lyle Najita najital at rockvax.rockefeller.edu
Sun May 21 08:11:48 EST 1995

In article <9505211608.AA25346 at phobos.med.pitt.edu>, bap at MED.PITT.EDU
(Bruce Phillips) wrote:

>         As per recent discussion on the role of VPg in picornavirus RNA
> replication and morphogenesis, I have never read or heard any discussion
> as to why animal cells, even rabbit reticulocytes (recall, rabbits don't
> get polio!) contain an enzymes that efficiently cleaves VPg from picorna-
> viral 5' RNA termini.  It suggests that there must exist eukaryotic(cellular)
> mRNAs with terminal proteins attached.  But such have never been reported
> to my knowledge.  If no such cellular mRNAs exist, what is the function of
> this seemingly ubiquitous enzyme in the cell?

It may be that the virus is using a cellular protease to unlink the VPg
from the mRNA. If that is the case, then there doesn't necessarily have to
be a cellular protein-linked RNA that would require a specific "unlinkase"
activity. If there were such linked RNAs, keep in mind also, that it
wouldn't necessarily have to be message. It could be a novel means of
capping an RNA or a unique, non-sequence specific form of localization.

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