scholarly journals Some transport properties of resealed washed human erythrocyte membranes

1978 ◽  
Vol 172 (3) ◽  
pp. 605-611 ◽  
Author(s):  
W J Mawby ◽  
J B C Findlay
Keyword(s):  
Glucose Transport ◽  
Human Erythrocyte ◽  
Phosphate Transport ◽  
Isolation Procedure ◽  
Transport Systems ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membranes ◽  
Membrane Isolation ◽  
Phosphate Exchange ◽  
Protein Mediator

A comparison was made between the phosphate- and glucose-transport systems of intact erythrocytes and resealed washed membranes. Glucose transport exhibits identical properties in both cases, but the phosphate-transport system does not appear to have survived the membrane isolation procedure unaltered. Evidence is presented to support the suggestion that some form of structural perturbation has occurred to the protein mediator of phosphate exchange.

Evidence against the Involvement of Mutarotase in the D-Glucose Uptake Activity of Isolated Human Erythrocyte Membranes

1972 ◽  
Vol 50 (9) ◽  
pp. 1028-1030 ◽  
Author(s):  
Arthur Kahlenberg ◽  
Gary Miller
Keyword(s):  
Glucose Uptake ◽  
Membrane Transport ◽  
Glucose Transport ◽  
Human Erythrocyte ◽  
Transport Process ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membranes ◽  
Uptake Activity ◽  
Glucose Carrier

Mutarotase, the enzyme catalyzing the interconversion of the anomeric forms of D-glucose, has recently been suggested to be the membrane glucose carrier in human erythrocytes. However, hemoglobin-free human erythrocyte membranes possessing D-glucose uptake activity were found to be free of mutarotase activity. Mutarotase activity was detected in the membrane-free hemolysates of the cells. It is therefore concluded that the D-glucose uptake activity of isolated erythrocyte membranes is not due to the binding of the sugar to mutarotase, and that this enzyme is not involved in glucose transport in a manner compatible with most presently held concepts of the membrane transport process.

scholarly journals Characterization and partial sequence of di-iodosulphophenyl isothiocyanate-binding peptide from human erythrocyte anion-transport protein

1982 ◽  
Vol 205 (3) ◽  
pp. 465-475 ◽  
Author(s):  
W J Mawby ◽  
J B Findlay
Keyword(s):  
Human Erythrocyte ◽  
Attachment Site ◽  
Phosphate Transport ◽  
Anion Transport ◽  
Transport Protein ◽  
Partial Sequence ◽  
Erythrocyte Membranes ◽  
Molecular Weights ◽  
Human Erythrocyte Membranes ◽  
Transmembrane Fragment

We investigated the presumed anion-binding domain of the anion-transport protein from human erythrocyte membranes, using 2,6-di-iodo-4-sulphophenyl isothiocyanate, an inhibitor of anion transport. The 125I-labelled reagent binds covalently to the protein with a half-maximal inhibitory concentration of 86 microM. Treatment of unsealed erythrocyte ‘ghosts’ with chymotrypsin yielded a membrane-bound fragment (mol.wt. 14 500 +/- 1000) that contained all the protein-bound radioactivity. The binding of the inhibitor to this peptide gave a pattern very similar to that obtained for the effect of the compound on phosphate transport into erythrocytes. The peptide is therefore presumed to be intimately involved in the mediation of anion exchange. Cleavage of the 14 500-mol.wt. transmembrane fragment with CNBr resulted in the production of two peptides with apparent molecular weights of 8800 and 4700. The 4700-mol.wt. peptide is the N-terminal portion of the 14 500-mol.wt. peptide. The attachment site for 2,6-di-iodo-4-sulphophenyl isothiocyanate is situated near the C-terminal of the 8800-mol.wt. peptide. This locates the inhibitor-binding site near the chymotrypsin cleavage point at the extracellular surface of the membrane. A partial sequence (residues 1-38) of the 8800-mol.wt. peptide was obtained.

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