Low-affinity glutamine synthetase. May contribute to the homeostatic control of glutamine synthesis in roots. ATP + L-glutamate + NH4(+) = ADP + H(+) + L-glutamine + phosphate Measured at pH 7.8 and 30 degrees Celsius for all experiments. Homooctamer (By similarity). Interacts with GRF3. A number of isoforms are produced. According to EST sequences. Expressed in the pericycle of all root tissues. By ammonium supply under nitrogen-limited condition. Induced by sucrose, glucose, fructose, and during leaf senescence. Belongs to the glutamine synthetase family.