This family consists of chloramphenicol (Cm) resistance gene leader peptides. Inducible resistance to Cm in both Gram positive and Gram negative bacteria is controlled by translation attenuation. In translation attenuation, the ribosome-binding-site (RBS) for the resistance determinant is sequestered in a secondary structure domain within the mRNA. Preceding the secondary structure is a short, translated ORF termed the leader. Ribosome stalling in the leader causes the destabilization of the downstream secondary structure, allowing initiation of translation of the Cm resistance gene.