This cationic N-terminal beta-sheet domain mediates binding of the class IIa bacteriocin to the target cell membrane.

These peptides act as pore-forming toxins that create cell membrane channels through a barrel-stave mechanism and thus produce an ionic imbalance in the cell[8] Other class II bacteriocins can be grouped together as Class IIc (circular bacteriocins).

Bacteriocin AS-48 is encoded by the pheromone-responsive plasmid pMB2, and acts on the plasma membrane in which it opens pores leading to ion leakage and cell death.

The mammalian NK-lysin effector protein of T and natural killer cells has a similar structure, though it lacks sequence homology with bacteriocins AS-48.

Class II bacteriocin and related families is variously recorded in Pfam and InterPro as: The naming is inconsistent at times.