VPg and its ramifications

[Bruce Phillips]

	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?