The approx. 70 residue Med15 domain of the ARC-Mediator co-activator is a three-helix bundle with marked similarity to the KIX domain. The sterol regulatory element binding protein (SREBP) family of transcription activators use the ARC105 subunit to activate target genes in the regulation of cholesterol and fatty acid homeostasis. In addition, Med15 is a critical transducer of gene activation signals that control early metazoan development [1].

1: An ARC/Mediator subunit required for SREBP control of cholesterol and lipid homeostasis. Yang F, Vought BW, Satterlee JS, Walker AK, Jim Sun ZY, Watts JL, DeBeaumont R, Saito RM, Hyberts SG, Yang S, Macol C, Iyer L, Tjian R, van den Heuvel S, Hart AC, Wagner G, Naar AM; Nature. 2006;442:700-704. PMID:16799563

2: Structure-system correlation identifies a gene regulatory Mediator submodule. Lariviere L, Seizl M, van Wageningen S, Rother S, van de Pasch L, Feldmann H, Strasser K, Hahn S, Holstege FC, Cramer P; Genes Dev. 2008;22:872-877. PMID:18381891

3: A unified nomenclature for protein subunits of mediator complexes linking transcriptional regulators to RNA polymerase II. Bourbon HM, Aguilera A, Ansari AZ, Asturias FJ, Berk AJ, Bjorklund S, Blackwell TK, Borggrefe T, Carey M, Carlson M, Conaway JW, Conaway RC, Emmons SW, Fondell JD, Freedman LP, Fukasawa T, Gustafsson CM, Han M, He X, Herman PK, Hinnebusch AG, Holmberg S, Mol Cell. 2004;14:553-557. PMID:15175151