Scaffolding protein involved in the icosahedric procapsid assembly. Coassembles with the capsid proteins to form the procapsid. The scaffolding protein is found within the capsid as a serie of concentric shells. During DNA packaging, the scaffolding protein molecules are released from the procapsid. Homodimer. Interacts non-specifically with DNA; probably binds DNA in the early stages of DNA packaging. Present in about 147 copies in the prohead but not present in mature virions. Belongs to the phi29likevirus scaffolding protein family.