Evidence for a Membrane Exchangeable Glucose Pool in the Functioning of Rat Liver Glucose-6-phosphatase (*)
Evidence for a Membrane Exchangeable Glucose Pool in the Functioning of Rat Liver Glucose-6-phosphatase (*)
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膜可交换葡萄糖池在大鼠肝脏葡萄糖 6 磷酸酶功能中的证据 (*)
DOI：
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发表时间：
1995
影响因子：
4.8
通讯作者：
G. van de Werve
中科院分区：
文献类型：
--
作者：
A. Berteloot;J. St;G. van de Werve
我们研究了示踪剂进入大鼠肝微粒体的动力学与葡萄糖6-磷酸酶（glu6 - pase）水解[14C]葡萄糖6-磷酸（glu6 -p）的关系。1)在快速（AMP1）和缓慢（AMP2）摄取阶段积累的囊泡内示踪剂的稳态水平均表现出相对于外部Glu-6-P浓度的Michaelis-Menten动力学，其K值与Glu-6-P水解的初始爆发(V)和稳态(V)速率相似。2)在整个外部Glu-6-P浓度范围内，AMP1/AMP2比值恒定（平均值= 0.105±0.018），等于AMP/AMP比值（0.109±0.032）。3)在缓慢摄取期（V2）葡萄糖初始转运速率与[AMP1]、[V]与[AMP2]之间观察到线性关系。4) V值超过V值的10倍以上。5)由此得出底物转运模型与这些结果不相容，AMP1代表一个膜交换性葡萄糖池。6)我们提出了一种新的构象模型，其中催化位点位于内在膜蛋白的亲水性口袋深处，并通过具有不同葡萄糖渗透率的通道与囊泡外和囊泡内空间通信。
We have investigated the kinetics of tracer uptake into rat liver microsomes in relation to [14C]glucose 6-phosphate (Glu-6-P) hydrolysis by glucose 6-phosphatase (Glu-6-Pase). 1) The steady-state levels of intravesicular tracer accumulated during the rapid (AMP1) and slow (AMP2) phases of uptake both demonstrate Michaelis-Menten kinetics relative to outside Glu-6-P concentrations with K values similar to those observed for the initial burst (V) and steady-state (V) rates of Glu-6-P hydrolysis. 2) The AMP1/AMP2 ratio is constant (mean value = 0.105 ± 0.018) over the whole range of outside Glu-6-P concentrations and is equal to the AMP/AMP ratio (0.109 ± 0.032). 3) Linear relationships are observed between the initial rates of glucose transport during the slow uptake phase (V2) and [AMP1], and between [V] and [AMP2]. 4) The value of V exceeds by more than 10-fold that of V. 5) It is concluded that the substrate transport model is incompatible with those results and that AMP1 represents a membrane exchangeable glucose pool. 6) We propose a new version of the conformational model in which the catalytic site lies deep within a hydrophilic pocket of an intrinsic membrane protein and communicates with the extra- and intravesicular spaces through channels with different glucose permeabilities.
微粒体葡萄糖-6-磷酸酶系统中磷酸盐和葡萄糖 6-磷酸参与独立易位的证据。
DOI：
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发表时间：
1980
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Arion,WJ;Lange,AJ;Walls,HE;Ballas,LM
通讯作者：
Ballas,LM