Plays an important role in the regulation of glutamine catabolism. Promotes mitochondrial respiration and increases ATP generation in cells by catalyzing the synthesis of glutamate and alpha-ketoglutarate. Increases cellular anti-oxidant function via NADH and glutathione production. May play a role in preventing tumor proliferation. H2O + L-glutamine = L-glutamate + NH4(+) Homotetramer, dimer of dimers (By similarity). Does not assemble into higher oligomers (By similarity). Interacts with the PDZ domain of the syntrophin SNTA1. Interacts with the PDZ domain of TAX1BP3 (By similarity). Liver specific. Belongs to the glutaminase family. Extended N-terminus.