Probably functions as a holin together with holin-like protein 26. Accumulates harmlessly in the cytoplasmic membrane until it reaches a critical concentration that triggers the formation of micron-scale pores (holes) causing host cell membrane disruption and endolysin escape into the periplasmic space. Determines the precise timing of host cell lysis. Counteracts the aggregation of the holin molecules and thus of pore formation. Homomultimer. Interacts with isoform Antiholin; this interaction blocks the holin homomultimerization and delays host cell lysis. Classified as a class II holin.