Structure. Monosialogangliosides (GM) belong to the group of gangliosides within the sphingolipids. Their structure consists of a ceramide backbone linked to an oligosaccharide. One of the sugar molecules is a sialic acid. The total number of sugar molecules is part of the name of GM subclasses: GM1 contains five sugars, GM2 four, GM3 three, and GM4 two. The ceramide backbone of monosialogangliosides contains two hydrocarbon chains: a long-chain base which is linked to a fatty acid via an amide bond. The fatty acid and the long-chain base can be of variable length, hydroxylated, and contain double bonds.
Function. The biological function of monosialogangliosides is mainly related to the neural system. GM1 gangliosides promote differentiation of neuronal cells, support neural stem cell proliferation, and inhibit neurodegeneration. GM4 gangliosides are a major part of myelin, the insulating layer that forms around the axons of neurons. The simplest gangliosides, GM3 gangliosides, are precursors to more complex gangliosides, and GM2 gangliosides are important components of mammal cell membranes. Accumulation of GMs leads a variety of diseases of which many impact cognitive capacity.
