This protein is an aporepressor. When complexed with L-tryptophan it binds the operator region of the trp operon (5'-ACTAGT-'3') and prevents the initiation of transcription. The complex also regulates trp repressor biosynthesis by binding to its regulatory region. Homodimer. Belongs to the TrpR family. PubMed:7841459 sequence was originally thought to originate from S.typhimurium, but seems to come from an unknown E.coli strain.