2 L-glutamate + NADP(+) = 2-oxoglutarate + H(+) + L-glutamine + NADPH Amino-acid biosynthesis; L-glutamate biosynthesis via GLT pathway; L-glutamate from 2-oxoglutarate and L-glutamine (NADP(+) route): step 1/1. Energy metabolism; nitrogen metabolism. Aggregate of 4 catalytic active heterodimers, consisting of a large and a small subunit. The gltAB operon is positively regulated by GltC and negatively regulated by TnrA under nitrogen-limited conditions. Belongs to the glutamate synthase family.