Cell-perforating component and plug protein of the phage tail machine (PubMed:18059287, PubMed:20817910). Together with gp4 and gp10, gp26 is required for stabilization of the condensed DNA within the capsid by plugging the hole through which the DNA enters (PubMed:18059287). Host cell membrane perforation allows viral DNA ejection (PubMed:18059287). The needle penetrates the host outer membrane. The needle is released and the internal head protein gp7 is ejected to form an extra-cellular channel (PubMed:30886360). Elongated coiled-coil homotrimer (240A x 25A). Interacts with gp10.