Absence of the major sialoglycoprotein in the membrane of human En(a--) erythrocytes and increased glycosylation of band 3.
The human En(a-) blood group is a rare recessive trait. These erythrocytes lack the major membrane sialoglycoprotein (PAS1, MN protein, or glycophorin) and contain a decreased amount of PAS2 as demonstrated by radiolabeling of surface porteins and chemical techniques. A third glycoprotein, Band 3, contains two labeled oligosaccharide chains; the more complex oligosaccharide has a higher molecular weight in En(1-) cells than in normal cells. A fourth glycoprotein, PAS3, is present in usual amounts in En(a-) cells. Cells heterozygous for En(a) are intermediate in these respects. The sialic acid is decreased in En(a-) cells, but the total carbohydrate is similar in the different membranes. The glycolipids are present in normal amounts but are much more exposed to galactose oxidase in En(a-) cells than in normal cells.
D000596:Amino Acids / Q000032:analysis; D001894:Borohydrides; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D004912:Erythrocytes / Q000378:metabolism* / Q000648:ultrastructure; D005808:Genes, Recessive; D006595:Hexosamines / Q000032:analysis; D006601:Hexoses / Q000032:analysis; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D012794:Sialic Acids / Q000032:analysis; D014166:Transferases / Q000097:blood*
D000596:Amino Acids; D001894:Borohydrides; D006595:Hexosamines; D006601:Hexoses; D012794:Sialic Acids; D014166:Transferases