gltb_C. This domain is found at the C-terminus of the large subunit (gltB) of glutamate synthase (GltS). GltS encodes a complex iron-sulfur flavoprotein that catalyzes the synthesis of L-glutamate from L-glutamine and 2-oxoglutarate. It requires the transfer of ammonia and electrons among three distinct active centers that carry out L-Gln hydrolysis, conversion of 2-oxoglutarate into L-Glu, and electron uptake from a donor. These catalytic sites appear to occur in other domains within the protein, and not the domain in this CD. This particular domain has no known function, but it likely has a structural role as it interacts with the amidotransferase and FMN-binding domains of gltS.