ASC-1 homology or ASCH domain, a small beta-barrel domain found in all three kingdoms of life. ASCH resembles the RNA-binding PUA domain and may also interact with RNA. ASCH has been proposed to function as an RNA-binding domain during coactivation, RNA-processing and the regulation of prokaryotic translation. The domain has been named after the ASC-1 protein, the activating signal cointegrator 1 or thyroid hormone receptor interactor protein 4 (TRIP4). ASC-1 is conserved in many eukaryotes and has been suggested to participate in a protein complex that interacts with RNA. It has been shown that ASC-1 mediates the interaction between various transciption factors and the basal transcriptional machinery.