Members of this protein family belong to the GNAT family of acetyltransferases. Each is part of a conserved three-gene cassette sparsely distributed across at least twenty different species known so far, including alpha, beta, and gamma Proteobacteria, Mycobacterium, and Prosthecochloris, which is a member of the Chlorobi. The other two members of the cassette are a probable protease and an asparagine synthetase family protein.