In some organisms, this enzyme is part of a multifunctional protein, together with one or more other components of the system for the biosynthesis of tryptophan [EC
2.4.2.18 (anthranilate phosphoribosyltransferase), EC
4.1.1.48 (indole-3-glycerol-phosphate synthase), EC
4.1.3.27 (anthranilate synthase) and EC
4.2.1.20 (tryptophan synthase)].