Plays an essential role in the viral genome replication. Participates, together with NSP2, in the formation of viral factories (viroplasms) which are large inclusions in the host cytoplasm where replication intermediates are assembled and viral RNA replication takes place. Orchestrates the recruitment of viroplasmic proteins such as capsid proteins to these factories. Magnesium is required for ATPase activity. Homodimer. Interacts with VP1. Interacts with VP2. Interacts with NSP2 and NSP6. Found in spherical cytoplasmic structures, called virus factories, that appear early after infection and are the site of viral replication and packaging. O-glycosylated. Belongs to the rotavirus NSP5 family.