[Erythrocyte membrane proteins]

Abstract

Proteins are important constituents of the red blood cell plasma membrane. Several important breakthroughs have occurred in their analysis over the past few years. SDS-polyacrylamide gel electrophoresis lead to the separation of the major proteins and glycoproteins. Location of most of these proteins -- either on the external, the internal or both surfaces of the membrane -- was determined. The strenght of the binding of the protein to the membrane was established. Hydrophobicity of membrane proteins has so far hindered their purification. However, the major glycoprotein (glycophorin A) was isolated and recently sequenced. The description of several membrane-associated enzyme activities has been followed by some understanding of their specific role in the red blood cell physiology. Abnormalities of glycoproteins, Ca2+-ATPase and of membrane protein phosphorylation have been reported under various conditions: sickle cell disease, hereditary spherocytoses, progressive muscular dystrophy.