Probable component of the transcriptional machinery present in the inner capsid. Displays dsRNA binding activity and may play an important role in the sorting of viral RNA and virion assembly. Together with the RNA-directed RNA polymerase P1 and capping enzyme P5, forms an transcriptional complex positioned near the channels situated at each of the five-fold vertices of the core (By similarity). Located inside the inner capsid. Found in the interior of spherical cytoplasmic structures, called virus factories, that appear early after infection and are the site of viral replication and packaging. Belongs to the phytoreovirus protein P7 family.