This entry represents the gp15 protein, the tail-sheath-stabiliser or tail-terminator protein of T4-like myoviridae phage. gp15 forms a hexamer and attaches to the top of the phage tail stabilising the contractile sheath and forming the interface for binding of the independently assembled head. The gp15 hexamer interacts with the gp3 hexamer and, presumably, with the C-terminal domains of gp18 molecules located in the last ring of the contractile sheath. It also creates the binding site for attachment of the capsid with mutant phage tails lacking gp15 being unable to join the heads. The tail binds to the head via interactions of gp15 with gp14 (or with both gp13 and gp14) since the latter form a complex that seals the portal vertex and creates an attachment site of the independently assembled tail PMID:23434847.