Structural and Biochemical Analysis of the McLeod Erythrocyte Membrane

Abstract

The abnormal erythrocyte of the McLeod phenotype displays a reduced Kell blood group expression, an abnormal morphology in .apprx. 30% of the total red blood cell population and a decrease in water permeability. These parameters were previously shown to be independent of membrane lipid composition, microviscosity and electrolyte transport. Findings such as these seem to implicate the involvement of a defective membrane protein. Membrane composition was investigated with freeze-fracture EM and discontinuous polyacrylamide gel electrophoresis. Electrophoretic scans revealed no apparent band additions or deletions showing McLeod membrane protein composition to be normal. Freeze-fracture EM did show a significant increase in intramembrane particle density. These findings may be resolved by proposing a dissociation of the band 3 glycoprotein. Unlinkage of this polypeptide, thought to be involved in water transport and intramembranous particle composition, could account for the decreased water transport and increased particle density seen in the McLeod erythrocyte membrane.