The RNA genome forms a nucleocapsid along with copies of the 12-kDa capsid protein. The nucleocapsid contains ~2000 copies of the capsid protein. A peplomer is a glycoprotein spike on a viral capsid or viral envelope. "Gag" encodes a polyprotein with a capsid and a nucleocapsid domain. There is an icosahedral configuration in the capsid of the herpes virus. The pgRNA is inserted into an assembled viral capsid containing the viral polymerase. A2 activity carried on the amino-terminal peptide of the capsid VP1 polypeptide. The envelope covers the T = 4 icosahedral capsid. Most viral structural proteins are components for the capsid and the envelope of the virus. Picornaviruses are non-enveloped, with an icosahedral capsid. Assembly of infectious particles needs interactions between the capsid and huge S within the cytoplasm. The late proteins form the capsid and the receptors on the surface of the virus. Complex viruses code for proteins that assist in the construction of their capsid. They underwent an elaborate maturation process involving protein cleavage and capsid expansion. This protein is encoded by a +1 frameshift in the capsid gene.