Inner capsid protein that plays a role in viral DNA ejection into the host cell (PubMed:26245366, PubMed:29590587). Assembles into an extracellular trans-envelope channel completed by the internal virion proteins gp7 and probably gp16 (PubMed:30886360). This channel allows the delivery of the viral genome into the cell cytoplasm (PubMed:30886360). Belongs to the podoviruses gp7 family.