The head-tail connector of bacteriophage 29 is composed of 12 36 kDa subunits with 12 fold symmetry. It is the central component of a rotary motor that packages the genomic dsDNA into pre-formed proheads. This motor consists of the head-tail connector, surrounded by a 29-encoded, 174-base, RNA and a viral ATPase protein [1,2].

1: Structure determination of the head-tail connector of bacteriophage phi29. Simpson AA, Leiman PG, Tao Y, He Y, Badasso MO, Jardine PJ, Anderson DL, Rossmann MG; Acta Crystallogr D Biol Crystallogr 2001;57:1260-1269. PMID:11526317

2: Structure of the bacteriophage phi29 DNA packaging motor. Simpson AA, Tao Y, Leiman PG, Badasso MO, He Y, Jardine PJ, Olson NH, Morais MC, Grimes S, Anderson DL, Baker TS, Rossmann MG; Nature 2000;408:745-750. PMID:11130079