About the structure and biological function of Gb4
Structure. Gb4 globoside lipids (globo-tetraosylceramides, or cytolipin R) belong to the group of globosides within the sphingolipids. Their structure consists of a ceramide backbone linked to a neutral oligosaccharide unit made of four sugar molecules. The ceramide backbone 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. Gb4 globosides are the main glycolipids found in the cell membrane of human erythrocytes. There, they are important for cellular interactions including blood-type determinants, factors which determine the suitability of donor blood for a patient. Each of the three distinct blood group antigens (A, B, and 0) is defined by a variation of the oligosaccharide unit. Gb4 lipids also act as the receptor for the parvovirus B19, which infects rapidly dividing cells of the intestines and the bone marrow causing (fifth disease) in children.
