Assembles to form an icosahedral capsid of 66 nm, with a T=7 laevo symmetry (PubMed:11000116, PubMed:21276801). Responsible for its self-assembly into a procapsid. The phage does not need to encode a separate scaffolfing protein because its capsid protein contains the delta domain that carries that function. Homopentamer and homohexamer; isoaspartyl lysine isopeptide-linked. Forms the icosahedral capsid shell which contains 420 major capsid proteins. The scaffolding domain delta has a role of scaffold allowing the self-assembly of the capsid protein. The scaffolding domain delta is cleaved by the viral protease and lost after assembly. The major capsid proteins are covalently cross-linked. Belongs to the HK97 phage major capsid protein family. Icosahedral capsid structure of expansion Intermediate IV Icosahedral capsid structure of head II Icosahedral capsid structure of head I mutant K169Y Icosahedral capsid structure of pepsin-treated Expansion Intermediate IV Icosahedral capsid structure of expansion Intermediate IV Icosahedral empty mature capsid structure