VPg
Encyclopedia
VPg is a protein attached to the 5' end of RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 during RNA synthesis in a wide variety of viruses including Picornaviridae such as Foot-and-mouth disease
Foot-and-mouth disease
Foot-and-mouth disease or hoof-and-mouth disease is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, including domestic and wild bovids...

 and poliovirus
Poliovirus
Poliovirus, the causative agent of poliomyelitis, is a human enterovirus and member of the family of Picornaviridae.Poliovirus is composed of an RNA genome and a protein capsid. The genome is a single-stranded positive-sense RNA genome that is about 7500 nucleotides long. The viral particle is...

 . VPg stands for "viral protein genome-linked".

Attachment during RNA synthesis

3CDpro (a protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....

) cleaves VPg from membrane-bound 3AB. 3Dpol (picornavirus
Picornavirus
A picornavirus is a virus belonging to the family Picornaviridae. Picornaviruses are non-enveloped, positive-stranded RNA viruses with an icosahedral capsid. The genome RNA is unusual because it has a protein on the 5' end that is used as a primer for transcription by RNA polymerase...

 RNA polymerase
RNA polymerase
RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...

) 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.

Sources

Principles of Virology by S.J. Flint, L.W. Enquist, V.R. Racaniello, A.M. Skalka (ISBN 1-55581-259-7)
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK