Reversibility of the specific adsorption of colicin E2-P9 to cells of colicin-sensitive strains of Escherichia coli.

The adsorption of colicin E2-P9 to its specific receptors on cells of sensitive strains of Escherichia coli is reversible under normal experimental conditions. At temperatures above 20 C, colicin may desorb from one cell and be readsorbed by a second with potentially lethal consequences. However, desorption of colicin seems unable to rescue a cell once it has received a lethal dose. These findings have implications both for the nature and types of specific receptors, and for the assay of colicin by the survivor count (lethal unit) methods.