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Specificity of the glucose transport system in Leishmania tropica promastigotes


, : Specificity of the glucose transport system in Leishmania tropica promastigotes. Journal of Protozoology 23(3): 446-449

The glucose transport system in Leishmania tropica promastigotes was characterized by the use of labeled 2-deoxy-D-glucose (2-DOG), a nonmetabolizable glucose analog. The uptake system has a Q10 of 2 and a heat of activation of 10.2 kcal/mole. The glucose transport system is subject to competitive inhibition by 2-DOG, glucosamine, N-acetyl glucosamine, mannose, galactose, and fructose which suggests that substitutions in the hexose chain at carbons 2 and 4 do not affect carrier specificity. In contrast, changes at carbon 1 (alpha-methyl-D-glucoside, 1,5-anhydroglucitol) and carbon 3 (3-0-methyl glucose) lead to loss of carrier affinity since these sugars do not compete for the glucose carrier. Sugars that compete with the glucose carrier have one common feature--they all exist in the pyranose form in solution. The carrier for D-glucose does not interact with L-glucose or any of the pentose sugars tested. Uptake of 2-DOG is inhibited by glycerol. This inhibition, however, is noncompetitive; it is evident; therefore, that glucose and glycerol do not compete for the same carrier. Glycerol does not repress the glucose carrier since cells grown in presence of glycerol transport the sugar normally.

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Accession: 006459063

PMID: 972353

DOI: 10.1111/j.1550-7408.1976.tb03810.x

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Related references

Schaefer, F.W.; Martin, E.; Mukkada, A.J., 1974: The glucose transport system in Leishmania tropica promastigotes. Journal of Protozoology 21(4): 592-596

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