Med26_C is the C-terminal domain of subunit 26 of the Mediator complex in eukaryotes. Med19 and Med26 act synergistically to mediate the interaction between REST (a Kruppel-type zinc finger transcription factor that binds to a 21-bp RE1 silencing element present in over 900 human genes) and Mediator [1]. The C-terminal domain is critical and sufficient for its assembly into Mediator and its interaction with Pol II. The most highly conserved C-terminal amino acids are critical for these interactions because deletion of the last eight amino acids from the Med26 C terminus disrupted binding to Mediator and Pol II [2].

1: MED19 and MED26 are synergistic functional targets of the RE1 silencing transcription factor in epigenetic silencing of neuronal gene expression. Ding N, Tomomori-Sato C, Sato S, Conaway RC, Conaway JW, Boyer TG; J Biol Chem. 2009;284:2648-2656. PMID:19049968

2: Human mediator subunit MED26 functions as a docking site for transcription elongation factors. Takahashi H, Parmely TJ, Sato S, Tomomori-Sato C, Banks CA, Kong SE, Szutorisz H, Swanson SK, Martin-Brown S, Washburn MP, Florens L, Seidel CW, Lin C, Smith ER, Shilatifard A, Conaway RC, Conaway JW; Cell. 2011;146:92-104. PMID:21729782