Functional incorporation of synthetic glycolipids into cells.

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Abstract
Synthetic glycolipids containing an .alpha.-mannoside group linked by a hydrophilic spacer arm to cholesterol were incorporated into bovine erythrocytes by exchange from glycolipid-containing liposomes. When the distance between the sugar and the cholesterol moieties was .apprx. 26 .ANG., functional incorporation of these glycolipids could be easily detected, as revealed by the concanavalin [Con] A-mediated agglutination of these cells. Bovine erythrocytes are not themselves susceptible to Con A-mediated agglutination. The minimal concentration of Con A required for agglutination of modified erythrocytes, containing 9.15 .times. 106 glycolipid molecules per cell, was 4 .mu.g/ml. Under these conditions, .apprx. 4% of the membrane-bound cholesterol had been exchanged for the synthetic glycolipid. The observed aggregation was reversible in the presence of .alpha.-methyl mannoside and did not occur when .beta.-galactosyl-containing glycolipids were used in place of their .alpha.-mannoside isomers. A technique of sugar incorporation into cell membranes is demonstrated which should be of great advantage in studies on the roles of cell surface sugars in biological recognition. The sugars apparently need only be a short distance (27 .ANG.) from the membrane to functionally bind Con A.