Abnormal blood-group-Ss-active sialoglycoproteins in the membrane of Miltenberger class III, IV and V human erythrocytes.
1. We have studied the inherited changes occurring in the sialoglycoproteins of membranes from erythrocytes of type Miltenberger Class III (Mi.III), Miltenberger Class IV (Mi.IV) and Miltenberger Class V (Mi.V) by using sodium dodecyl sulphate/polyacrylamide gel electrophoresis and lactoperoxidase radioiodination. 2. Mi.III erythrocytes lack the normal blood-group-Ss-active sialoglycoprotein but contain an unusual s-active sialoglycoprotein of higher apparent molecular weight. A similar abnormal S-active sialoglycoprotein appears to occur in Mi.IV erythrocytes. 3. The Mi.V condition is associated with the hemizygous absence of both the normal blood-group-MN-active sialoglycoprotein and the normal Ss-active sialoglycorprotein. However, a new sialoglycoprotein component is present in these cells that has properties characteristic of both the MN-active and Ss-active sialoglycoproteins. 4. Our results suggest that the new sialoglycorportein present in Mi.V erythrocytes is a hybrid of the normal MN sialoglycoprotein and an s-active sialoglycoprotein that has properties similar to the s-active sialoglycoprotein found in Mi.III erythrocytes. We suggest that the unusual Mi.V sialoglycoprotein is derived from chromosomal misalignment with unequal crossing-over between the genes for the MN- and Ss-active sialoglycoproteins in a manner similar to that which gives rise to haemoglobin Lepore. 5. Further studies of S-s-erythrocytes confirm that these cells lack normal Ss-active sialoglycoprotein, but contain an unusual component that shows some of the properties of the normal Ss-active sialoglycoprotein. 6. Analysis of erythrocytes of type Mk/Mi.III confirms that, in addition to the known hemizygous lack of the MN-active sialoglycoprotein, the Mk condition is also associated with a loss of the Ss-active sialoglycoprotein. 7. In order to facilitate discussion of the complex changes that occur in these variant erythrocytes, a new unified nomenclature is used for the erythrocyte sialoglycoproteins.
D001345:Autoradiography; D003434:Crossing Over, Genetic; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000032:analysis*; D004912:Erythrocytes / Q000032:analysis*; D006021:Glycophorins / Q000032:analysis* / Q000145:classification / Q000235:genetics; D006801:Humans; D007784:Lactoperoxidase; D008951:MNSs Blood-Group System; D010504:Periodic Acid; D012795:Sialoglycoproteins / Q000032:analysis*; D009626:Terminology as Topic
D006021:Glycophorins; D008951:MNSs Blood-Group System; D012795:Sialoglycoproteins; D010504:Periodic Acid; D007784:Lactoperoxidase