The members of this family are all similar to chloramphenicol 3-O phosphotransferase (CPT, Swiss:Q56148) expressed by Streptomyces venezuelae. Chloramphenicol (Cm) is a metabolite produced by this bacterium that can inhibit ribosomal peptidyl transferase activity and therefore protein production. By transferring a phosphate group to the C-3 hydroxyl group of Cm, CPT inactivates this potentially lethal metabolite [1].

1: Structural basis for chloramphenicol tolerance in Streptomyces venezuelae by chloramphenicol phosphotransferase activity. Izard T; Protein Sci 2001;10:1508-1513. PMID:11468347