Rapid GLUT-1 mediated glucose transport in erythrocytes from the grey-headed fruit bat (Pteropus poliocephalus).
D-Glucose entry into erythrocytes from adult grey-headed flying fox fruit bats (Pteropus poliocephalus) was rapid and showed saturation at high substrate concentrations. Kinetic parameters were estimated from the concentration dependence of initial rates of zero-trans D-glucose entry at 5.5 degrees C as Michaelis constant (K(m)) 1. 64+/-0.56 mM, and maximal velocity (V(max)) 1162+/-152 micromol.l. cell water(-1).min(-1). D-Glucose entry was inhibited by cytochalasin B; mass law analysis of D-glucose-displaceable cytochalasin B binding gave values of K(d) 37.1+/-5.0 nM and B(max) 361.2+/-9.1 pmol/mg membrane protein. Entry of 2-deoxy-D-glucose, and 3-O-methyl-D-glucose, into P. poliocephalus red cells was rapid, entry of D-fructose was very slow. Glucose transporter polypeptides were identified on immunoblots as a band M(r) 47000-54000 and their identity confirmed by D-glucose-sensitive photolabeling of membranes with [3H]-cytochalasin B. Peptide-N-glycanase F digestion of both human and bat erythrocyte membranes generated GLUT-1-derived bands M(r) 37000. Trypsin digestion of human and fruit bat erythrocyte membranes generated fragmentation patterns consistent with similar GLUT-1 polypeptide structures in both species. Erythrocytes from adult Australian ghost bats (Macroderma gigas), a carnivorous microchiropteran bat, also expressed high levels of GLUT-1.
Craik
J D
JD
Department of Biochemistry, Faculty of Medicine, Kuwait University, Safat, Kuwait. james@hsc.kuniv.edu.kw
Markovich
D
D
D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D001692:Biological Transport / Q000187:drug effects; D002463:Cell Membrane Permeability; D002685:Chiroptera / Q000378:metabolism*; D003571:Cytochalasin B / Q000737:chemistry / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism* / Q000493:pharmacokinetics; D051272:Glucose Transporter Type 1; D015151:Immunoblotting; D009004:Monosaccharide Transport Proteins / Q000032:analysis / Q000378:metabolism*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D010777:Photochemistry; D014316:Tritium; D014357:Trypsin / Q000378:metabolism
D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D014316:Tritium; D003571:Cytochalasin B; D014357:Trypsin; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D005947:Glucose