Part of a heterotetrameric complex that catalyzes the two-step biosynthesis of anthranilate, an intermediate in the biosynthesis of L-tryptophan. In the first step, the glutamine-binding beta subunit of anthranilate synthase (AS) provides the glutamine amidotransferase activity which generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by the large alpha subunit of AS to produce anthranilate. chorismate + L-glutamine = anthranilate + H(+) + L-glutamate + pyruvate Feedback inhibition by tryptophan. kcat is 14.6 sec(-1) with chorismate as substrate (for recombinant ASA2 and ASB1 proteins synthesized with the wheat germ cell-free system). Amino-acid biosynthesis; L-tryptophan biosynthesis; L-tryptophan from chorismate: step 1/5. Heterotetramer consisting of two non-identical subunits: a beta subunit and a large alpha subunit. By chitin oligosaccharide elicitor and the phytopathogenic fungus Bipolaris oryzae. Belongs to the anthranilate synthase component I family.