抄録
The TRAP/Mediator complex is a metazoan, phylogenetically-conserved, transcriptional regulatory complex. It was originally isolated as a thyroid hormone receptor (TR)-associated protein (TRAP) complex that mediates TR-activated transcription from DNA templates in vitro and probably acts in vivo after the action of other receptor-interacting coactivators involved in chromatin remodeling. The TRAP complex was subsequently re-identified as the metazoan counterpart of the yeast Mediator complex, which is more broadly used for a wide variety of activators. In mammals, solely the TRAP220 subunit mediates ligand-dependent interactions of the complex with nuclear receptors. In contrast to murine Srb7 that is essential for cell viability per se, genetic ablations of murine TRAP220 and TRAP100 subunits have revealed that they are not but are both early embryonic lethal. These studies have also revealed the activator (e.g., nuclear receptor)-specific roles of TRAP220 in various physiological events (such as in adipogenesis and pituitary-thyroid axis) and the roles of TRAP100 in broad transcriptional events. These phenotypic and mechanistic distinctions between TRAP220 and TRAP100 knockouts contrast their many similarities, and indicate the specificity of these subunits (and probably other subunits) in the roles of the complex both for optimal activators functions and for a variety of early developmental and adult homeostasis events in mice. [Jpn J Physiol 54 Suppl:S52 (2004)]
