Molecular Genetics of Human Erythrocyte Sialoglycoproteins Glycophorins A, B, C, and D

The membrane of human erythrocytes has been a model system for studying the structure and function of the plasma membrane. By analyzing the components of the human erythrocyte membrane, the most important concepts in membrane biochemistry and biology have been borne out. Isolation and characterization of a major erythrocyte sialoglycoprotein, now called glycophorin A, provided the essential characteristics of trans-membrane glycoprotein (Tomita and Marchesi, 1975). Membrane proteins associated less strongly with the lipid bilayer—peripheral proteins—were recognized at the same time (Singer and Nicolson, 1972). The erythrocyte cytoskeleton was identified by investigation of the interaction of these proteins with the filamentous network beneath the lipid bilayer (Yu et al.,1973). Thus, this system provides an interesting model for studying the structure and organization of membrane glycoproteins, how those glycoproteins interact with other proteins, and cytoskeletal protein interactions. Furthermore, the structural change of cell-surface carbohydrates during development was elucidated for the first time in this system (Fukuda et al., 1979), which corresponds to fetal (i) and to adult (I) erythrocyte antigens.