This domain is found in many signalling proteins in which it functions as a sensor domain. It recognises FMN, Zn(II), FAD and riboflavin (MAtilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).
ANTAR (AmiR and NasR transcription antitermination regulators) is an RNA-binding domain found in bacterial transcription antitermination regulatory proteins. The majority of the domain consists of a coiled-coil.