The glucose transport system of membrane vesicles isolated from Acholeplasma laidlawii is saturable, with a Km of 21.2 mum and V of 0.68 nmol min-1 (mg protein)-1. The process is pH-dependent and a break occurs in the Arrhenius plot at 15 degrees C. Exogenous substrates did not stimulate glucose transport probably due to their inability to penetrate into membrane vesicles. 3-O-Methylglucose and 6-deoxyglucose competitively inhibited glucose transport. Maltose inhibited transport of glucose noncompetitively. These sugars also elicited glucose efflux from preloaded membrane vesicles.

• MeSH
• Acholeplasma laidlawii metabolism   MeSH
• Biological Transport, Active MeSH
• Cell Membrane metabolism   MeSH
• Deoxyglucose metabolism   MeSH
• Glucose metabolism   MeSH
• Kinetics MeSH
• Hydrogen-Ion Concentration MeSH
• Maltose metabolism   MeSH
• Methylglucosides metabolism   MeSH
• Subcellular Fractions MeSH
• Temperature MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Deoxyglucose MeSH
• Glucose MeSH
• Maltose MeSH
• Methylglucosides MeSH

Membrane vesicles obtained from Acholeplasma laidlawii accumulate glucose as well as maltose and fructose against their concentration gradient in the absence of exogenous energy sources. Glucose uptake by membrane vesicles is inhibited by anaerobiosis and by electron transfer inhibitors, such as rotenone and amytal, but not by 2-heptyl-4-hydroxyquinoline N-oxide, antimycin A, cyanide and azide. Rotenone, cyanide and amytal also produce a rapid efflux of glucose from the membrane vesicles. Arsenate, oligomycin and N,N'-dicyclohexylcarbodimide do not inhibit glucose transport. Transport of glucose is markedly inhibited by proton conductors such as CCCP and pentachlorophenol. It is concluded that glucose transport can be driven by a high-energy state of the membrane or by the membrane potential.

• MeSH
• Acholeplasma laidlawii metabolism   MeSH
• Biological Transport, Active drug effects   MeSH
• Amobarbital pharmacology   MeSH
• Anaerobiosis MeSH
• Cell Membrane metabolism   MeSH
• Depression, Chemical MeSH
• Fructose metabolism   MeSH
• Glucose metabolism   MeSH
• Maltose metabolism   MeSH
• Rotenone pharmacology   MeSH
• Uncoupling Agents pharmacology   MeSH
• Subcellular Fractions MeSH
• Sulfhydryl Reagents pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Amobarbital MeSH
• Fructose MeSH
• Glucose MeSH
• Maltose MeSH
• Rotenone MeSH
• Uncoupling Agents MeSH
• Sulfhydryl Reagents MeSH