STUDIES OF THE METABOLISM OF HUMAN ERYTHROCYTE MEMBRANES*

Abstract

These investigations were undertaken to discover whether membranes of mature human erythrocytes are capable of metabolic activity that could possibly provide the means for active transport. Erythrocyte membranes prepared by dialysis of whole erythrocytes against increasingly hypotonic salt solutions retained their biconcave disk shape, were generally free of distortion, and contained 0.03% of their original hemoglobin. These membranes have a characteristic pattern of enzyme values which is strikingly different from the pattern of enzyme values in whole hemolysates. Membranes contain the glyceraldehyde phosphate dehydrogenase-phosphoglycerate kinase complex, together with a triple enzyme sequence of the pentose phosphate pathway consisting of phosphoribiosomerase, phosphoketopentose epimerase, and transketolase. The presence of these enzymes in membranes could account for the experimental observations regarding inorganic phosphate transport in erythrocytes. Furthermore, the presence of glyceraldehyde phosphate dehydrogenase-phosphoglycerate kinase raises the possibility of local ATP production in membranes.