Controls the flux of glucose into the hexosamine pathway. Most likely involved in regulating the availability of precursors for N- and O-linked glycosylation of proteins. Regulates the circadian expression of clock genes ARNTL/BMAL1 and CRY1 (PubMed:10898949). Has a role in fine tuning the metabolic fluctuations of cytosolic UDP-GlcNAc and its effects on hyaluronan synthesis that occur during tissue remodeling (By similarity). D-fructose 6-phosphate + L-glutamine = D-glucosamine 6-phosphate + L-glutamate Inhibited by 4,4'-dithiodipyridine. Optimum pH is 7.5. Nucleotide-sugar biosynthesis; UDP-N-acetyl-alpha-D-glucosamine biosynthesis; alpha-D-glucosamine 6-phosphate from D-fructose 6-phosphate: step 1/1. Homotetramer, may also exist as homodimers.