Weak n activity of en(a−) human erythrocyte membranes

The propositus's erythrocytes with phenotype En(a−), which was found for the first time in a Japanese family, reacted more weakly with anti‐N serum than the ordinary phenotype N erythrocytes. The En(a−) erythrocytes lack the major membrane sialoglycoprotein (glycophorin A) as demonstrated by Bio‐Gel 1.5m gel filtration from active sialoglycoproteins, which were isolated from En(a−) erythrocyte membranes by the method of lithium diiodosalicylate (LIS)‐phenol extraction. It is suggested from observation via enzymelinked immunosorbent assay (ELISA) that N activity is derived from the glycophorin B molecule on En(a−) erythrocyte membranes. © 1993 Wiley‐Liss, Inc.