Hol_Tox is a family of small proteins (34-48aas) with a single TM region. Members can exhibit antibacterial activity against Gram-positive bacteria but not against Gram-negative bacteria [1].

1: Functional characterization of a new holin-like antibacterial protein coding gene tmp1 from goat skin surface metagenome. Rajesh T, Anthony T, Saranya S, Pushpam PL, Gunasekaran P; Appl Microbiol Biotechnol. 2011;89:1061-1073. PMID:20927512