Glutamine synthetase that catalyzes the ATP-dependent conversion of glutamate and ammonia to glutamine (By similarity). Its role depends on tissue localization: in the brain, it regulates the levels of toxic ammonia and converts neurotoxic glutamate to harmless glutamine, whereas in the liver, it is one of the enzymes responsible for the removal of ammonia (PubMed:25870278). Essential for proliferation of fetal skin fibroblasts (By similarity). Independently of its glutamine synthetase activity, required for endothelial cell migration during vascular development (PubMed:30158707). Involved in angiogenesis by regulating membrane localization and activation of the GTPase RHOJ, possibly by promoting RHOJ palmitoylation (By similarity). May act as a palmitoyltransferase for RHOJ: able to autopalmitoylate and then transfer the palmitoyl group to RHOJ (By similarity). Plays a role in ribosomal 40S subunit biogenesis (By similarity). ATP + L-glutamate + NH4(+) = ADP + H(+) + L-glutamine + phosphate hexadecanoyl-CoA + L-cysteinyl-[protein] = CoA + S-hexadecanoyl-L-cysteinyl-[protein] Glutamine synthetase activity is inhibited by methionine sulfoximine (MSO). Decamer; composed of two pentamers (By similarity). Interacts with PALMD (PubMed:16323283). Interacts with RHOJ (By similarity). Mainly localizes in the cytosol, with a fraction associated with the cell membrane. Expressed in microvascular endothelial cells. Palmitoylated; undergoes autopalmitoylation. Ubiquitinated by ZNRF1. Embryonic lethality when embryos move from the uterine tube to the uterine environment (PubMed:17557305). Conditional deletion in the liver leads to a marked increase of plasma ammonia levels, causing increased locomotion, impaired fear memory and a slightly reduced life span (PubMed:25870278). Conditional deletion in endothelial cells impairs vessel sprouting during vascular development due to defects in endothelial cell migration (PubMed:30158707). Belongs to the glutamine synthetase family.