This is a family of transcriptional regulators. In mammals, it activates the transcription of mitochondrially-encoded COX1 [2]. In bacteria, it negatively regulates the quorum-sensing response regulator by binding to its promoter region [3]. This entry represents the second and third domains in this protein, with one domain nested within the other.

1: Crystal structure of conserved hypothetical protein Aq1575 from Aquifex aeolicus. Shin DH, Yokota H, Kim R, Kim SH; Proc Natl Acad Sci U S A. 2002;99:7980-7985. PMID:12060744

2: Mutation in TACO1, encoding a translational activator of COX I, results in cytochrome c oxidase deficiency and late-onset Leigh syndrome. Weraarpachai W, Antonicka H, Sasarman F, Seeger J, Schrank B, Kolesar JE, Lochmuller H, Chevrette M, Kaufman BA, Horvath R, Shoubridge EA; Nat Genet. 2009;41:833-837. PMID:19503089

3: The YebC family protein PA0964 negatively regulates the Pseudomonas aeruginosa quinolone signal system and pyocyanin production. Liang H, Li L, Dong Z, Surette MG, Duan K; J Bacteriol. 2008;190:6217-6227. PMID:18641136