<p>This entry consists of several bacterial zeta toxin proteins. Zeta toxin is thought to be part of a postregulational killing (PSK) system involved in the killing of plasmid-free cells. It relies on antitoxin/toxin systems that secure stable inheritance of low and medium copy number plasmids during cell division and kill cells that have lost the plasmid [<cite idref="PUB00012377"/>].</p> Zeta toxin