This family of proteins includes the SdpI and YfhL proteins from B. subtilis. The SdpI protein is a multipass integral membrane protein that protects toxin-producing cells from being killed. Killing is mediated by the exported toxic protein SdpC an extracellular protein that induces the synthesis of an immunity protein [1].

1: A three-protein signaling pathway governing immunity to a bacterial cannibalism toxin. Ellermeier CD, Hobbs EC, Gonzalez-Pastor JE, Losick R; Cell. 2006;124:549-559. PMID:16469701