Light-modulated chloroplastic glutamine synthetase, encoded by a nuclear gene and expressed primarily in leaves, and which is responsible for the reassimilation of the ammonia generated by photorespiration. ATP + L-glutamate + NH4(+) = ADP + H(+) + L-glutamine + phosphate Homooctamer. Plants overexpressing GLN2 show enhanced photorespiration capacity. Belongs to the glutamine synthetase family.