This protein forms a hole, or portal, that enables DNA passage during packaging and ejection. It also forms the junction between the phage head (capsid) and the tail proteins. During SPP1 morphogenesis, Gp6 participates in the procapsid assembly reaction. This family also includes the old Pfam family Phage_min_cap (PF05126).
Lu S et al.(2020). "CDD/SPARCLE: the conserved domain database in 2020.",