It is part of a biopolymer in the bacterial cell wall, which is built from alternating units of GlcNAc and N-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein).
O-GlcNAcylation is the process of adding a single N-acetylglucosamine sugar to the serine or threonine of a protein.[4] Comparable to phosphorylation, addition or removal of N-acetylglucosamine is a means of activating or deactivating enzymes or transcription factors.[4] In fact, O-GlcNAcylation and phosphorylation often compete for the same serine/threonine sites.[4]O-GlcNAcylation most often occurs on chromatin proteins, and is often seen as a response to stress.[4]
Hyperglycemia increases O-GlcNAcylation, leading to insulin resistance.[5] Increased O-GlcNAcylation due to hyperglycemia is evidently a dysfunctional form of O-GlcNAcylation. O-GlcNAcylation decline in the brain with age is associated with cognitive decline. When O-GlcNAcylation was increased in the hippocampus of aged mice, spatial learning and memory improved.[6]
^Kamel M, Hanafi M, Bassiouni M (1991). "Inhibition of elastase enzyme release from human polymorphonuclear leukocytes by N-acetyl-galactosamine and N-acetyl-glucosamine". Clinical and Experimental Rheumatology. 9 (1): 17–21. PMID2054963.
