Catalyzes the reversible oxidative deamination of glutamate to alpha-ketoglutarate and ammonia. H2O + L-glutamate + NADP(+) = 2-oxoglutarate + H(+) + NADPH + NH4(+) Competitively inhibited by homoserine and by glutamine. Optimum pH is 8 and 9 for the reductive amination and for the oxidative deamination, respectively. The enzyme remains active when heat treated or when left at room temperature for several months but is inactivated by freezing. Homohexamer. Induced by growth on glucose and ammonia. Belongs to the Glu/Leu/Phe/Val dehydrogenases family.