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 mu mol . 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 47 000-54 000 and their identity confirmed by D-glucose-sensitive photolabeling of membranes with [H-3]-cytochalasin B. Peptide-N-glycanase F digestion of both human and bat erythrocyte membranes generated GLUT-1-derived bands M-r 37 000. 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. (C) 2000 Elsevier Science Inc. All rights reserved