Schematic presentation of two models of holin hole formation. Holin monomers (shaded circles) are produced in the cytoplasm, and then transported to the cell membrane (a top-down view of the cell membrane thereafter) where they dimerize. A previous model (open arrows) [28, 39] hypothesized that the growth of the holin aggregates ("rafts") to a critical size that is responsible for the collapse of the proton motive force (pmf), thus resulting in hole formation. The current model  (filled arrows) suggests that the holin proteins are mostly in a mobile state, then quite suddenly, aggregates are formed, leading to the formation of holin holes. Addition of the energy poison KCN halts further holin production and abolishes the pmf. This figure is adapted from Wang et al.  and White et al. .