lipopolysaccharide biosynthesis lipid IV(A) biosynthesis PMID:17163638 UPa:UPA00359 2,3,2',3'-tetrakis(3-hydroxytetradecanoyl)-D-glucosaminyl-1,6-beta-D-glucosamine 1,4'-bis(dihydrogen phosphate) biosynthesis pathway KEGG:map00540 Biosynthesis of lipid IV(A), the endotoxically inactive LPS lipid A precursor. Lipid A is one of the three components of lipopolysaccharide (LPS). It contains unusual fatty acids (e.g. hydroxy-myristic acid) and is inserted into the outer membrane while the rest of the LPS projects from the surface. Lipid A, the potent macrophage-activating component primarily responsible for LPS endotoxin activity, is a phosphorylated glucosamine disaccharide carrying long-chain saturated fatty acid (FA) substituents that anchor LPS in the outer membrane. Lipid A is similar for all Gram-negative Enterobacteriaceae, and synthetic lipid A produces effects identical to that isolated from Escherichia coli in both in vitro and in vivo endotoxin tests. KEGG:map01100 glycolipid biosynthesis