VPg

VPg is a protein attached to the 5' end of RNA during RNA synthesis in a wide variety of viruses including Poliovirus and Picornavirus. VPg stands for "viral protein genome-linked".

Attachment during RNA synthesis
3CDpro (a protease) cleaves VPg from membrane-bound 3AB. 3Dpol (polivirus' RNA polymerase) then synthesizes VPg-pUpU using the sequence AAACA from the cre (cis-acting replication element) of the template strand. The 3Dpol-VPg-pUpU complex then moves to the 3' poly(A) tail of the template strand and commences RNA synthesis using the pUpU sequence as a primer.