title: Cytochalasin B does not serve as a marker of glucose transport in rabbit erythrocytes.
abstract: Glucose inhibitable cytochalasin B binding to erythrocyte membranes has been used as a marker of the glucose transporter. Glucose transport and cytochalasin B binding in rabbit erythrocytes differ from those activities found in human erythrocytes. We evaluated the uptake of 3-0-methylglucose and found similar Km (4.81 +/- 1.20 mM (SEM) and 6.59 +/- 0.72 mM) though significantly different Vmax (5.2 +/- 0.7 nM . min-1/10(9) cells and 234 +/- 13 nM X min -1/10(9) cells, p less than 0.001) for rabbit and human erythrocytes, respectively. Equilibrium binding of cytochalasin B to human erythrocyte membranes demonstrates a high affinity cytochalasin B binding site (Kd 38.6 +/- 22.7 nM) which is displaced by glucose. No comparable glucose inhibitable cytochalasin B site exists for rabbit erythrocyte membranes. Photoaffinity labeling of cytochalasin B confirms the presence of a glucose inhibitable cytochalasin B binding site in human, but not rabbit erythrocyte membranes. Cytochalasin B binding is a useful method in the identification of the glucose transporter in human cells, but the technique may be less useful in other species.
mesh_terms: D019325:3-O-Methylglucose; D000818:Animals; D001693:Biological Transport, Active; D001786:Blood Glucose / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D003571:Cytochalasin B / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008757:Methylglucosides / Q000097:blood; D009004:Monosaccharide Transport Proteins; D010782:Photolysis; D011817:Rabbits
chemical_list: D001786:Blood Glucose; D002352:Carrier Proteins; D008757:Methylglucosides; D009004:Monosaccharide Transport Proteins; D019325:3-O-Methylglucose; D003571:Cytochalasin B