葡萄糖转运对布氏锥虫糖酵解通量控制的贡献。
Contribution of glucose transport to the control of the glycolytic flux in Trypanosoma brucei.
作者信息
Bakker B M, Walsh M C, ter Kuile B H, Mensonides F I, Michels P A, Opperdoes F R, Westerhoff H V
机构信息
Molecular Cell Physiology, BioCentrum Amsterdam, Vrije Universiteit, De Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands.
出版信息
Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10098-103. doi: 10.1073/pnas.96.18.10098.
The rate of glucose transport across the plasma membrane of the bloodstream form of Trypanosoma brucei was modulated by titration of the hexose transporter with the inhibitor phloretin, and the effect on the glycolytic flux was measured. A rapid glucose uptake assay was developed to measure the transport activity independently of the glycolytic flux. Phloretin proved a competitive inhibitor. When the effect of the intracellular glucose concentration on the inhibition was taken into account, the flux control coefficient of the glucose transporter was between 0.3 and 0.5 at 5 mM glucose. Because the flux control coefficients of all steps in a metabolic pathway sum to 1, this result proves that glucose transport is not the rate-limiting step of trypanosome glycolysis. Under physiological conditions, transport shares the control with other steps. At glucose concentrations much lower than physiological, the glucose carrier assumed all control, in close agreement with model predictions.
通过用抑制剂根皮素滴定己糖转运蛋白来调节布氏锥虫血流形式的质膜上葡萄糖的转运速率，并测量其对糖酵解通量的影响。开发了一种快速葡萄糖摄取测定法，以独立于糖酵解通量来测量转运活性。根皮素被证明是一种竞争性抑制剂。当考虑细胞内葡萄糖浓度对抑制作用的影响时，在5 mM葡萄糖浓度下，葡萄糖转运蛋白的通量控制系数在0.3至0.5之间。由于代谢途径中所有步骤的通量控制系数之和为1，这一结果证明葡萄糖转运不是锥虫糖酵解的限速步骤。在生理条件下，转运与其他步骤共同控制。在远低于生理浓度的葡萄糖浓度下，葡萄糖载体承担了所有的控制作用，这与模型预测结果非常吻合。
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