FROM LEGUMES TO LEUKOCYTES - BIOLOGICAL ROLES FOR SULFATED CARBOHYDRATES

Carbohydrates attached to proteins and lipids characteristically displ ay complex and heterogeneous structures. However, it is becoming incre asingly clear that carbohydrates with definite biological functions al so exhibit unique structural features. A number of glycoproteins and g lycolipids have been shown to bear oligosaccharides containing sulfate , Often, addition of a sulfate moiety turns a relatively common struct ural motif into a unique carbohydrate with the potential to be recogni zed by a specific receptor or lectin. This is clearly the case in thre e systems in which sulfated oligosaccharides have been shown to play a well-defined biological role: 1) control of the circulatory half-life of luteinizing hormone, 2) symbiotic interactions be tween leguminous plants and nitrogen-fixing bacteria, and 3) homing of lymphocytes to lymph nodes. The rapidly growing list of glycoproteins and glycolipids identified as bearing sulfated oligosaccharides suggests that sulfate d carbohydrates play important biological roles in numerous other syst ems as well.