Low-affinity glutamine synthetase (PubMed:14757761). 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. Expressed in the pericycle in the region of mature root. By sucrose, glucose and fructose. Down-regulated by ammonium supply. Belongs to the glutamine synthetase family.