INSIGHTS INTO THE STRUCTURE AND FUNCTION OF MEMBRANE POLYPEPTIDES CARRYING BLOOD-GROUP ANTIGENS

In recent years, advances in biochemistry and molecular genetics have contributed to establishing the structure of the genes and proteins fr om most of the 23 blood group systems presently known. Current investi gations are focusing on genetic polymorphism analysis, tissue-specific expression, biological properties and structure-function relationship s. On the basis of this information, the blood group antigens were ten tatively classified into five functional categories: (i) transporters and channels, (ii) receptors for exogenous ligands, viruses, bacteria and parasites, (iii) adhesion molecules, (iv) enzymes and, (v) structu ral proteins. This review will focus on selected blood groups systems (RH, JK, FY, LU, LW, KEL and XK) which are representative of these cla sses of molecules, in order to illustrate how these studies may bring new information on common and variant phenotypes and for understanding both the mechanisms of tissue specific expression and the potential f unction of these antigens, particularly those expressed in nonerythroi d lineage.