Lipoglycans from mycoplasmas.
Lipoglycans , distinguishable from bacterial lipopolysaccharides, are associated with the cytoplasmic membranes of several genera of Mollicutes, namely Acholeplasma, Mycoplasma neurolyticum , Anaeroplasma , and Thermoplasma. Structurally, the lipoglycans are long heteropolysaccharides covalently linked to a lipid. The exact structures of three have been determined. Thermoplasma oligosaccharide is attached to a diglycerol tetraether ; A. granularum to a diacyl glycerol. The lipoglycan from A. axanthum is unique by its possession of glycerol phosphate and galactose phosphate side chains and the occurrence of fatty acids in N-acyl linkages. Only one molecular species of lipoglycan occurs in a given species. These lipoglycans possess a variety of biological activities. The terminal three sugar residues define their antigenic specificity; they attach to specific receptors on mammalian cells; they exhibit pyrogenicity in rabbits and clot Limulus lysate; they stimulate the production of IgM antibody both in vivo and in vitro; they modulate the immune response to T-cell dependent antigens; they exhibit immunosuppressive and immunostimulatory activities.
D000127:Acholeplasma / Q000032:analysis; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D000942:Antigens, Bacterial / Q000276:immunology; D001435:Bacteriophages / Q000378:metabolism; D002462:Cell Membrane / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D004912:Erythrocytes / Q000378:metabolism; D008070:Lipopolysaccharides / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D046911:Macromolecular Substances; D008855:Microscopy, Electron, Scanning; D009174:Mycoplasma / Q000032:analysis; D009179:Mycoplasmatales / Q000032:analysis* / Q000276:immunology; D013149:Spiroplasma / Q000032:analysis; D013822:Thermoplasma / Q000032:analysis
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D046911:Macromolecular Substances