Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms.
Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms.
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DOI：
10.1096/fj.14-267773
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发表时间：
2015-06
期刊：
影响因子：
--
通讯作者：
Glazier JD
中科院分区：
文献类型：
--
作者：
Widdows KL;Panitchob N;Crocker IP;Please CP;Hanson MA;Sibley CP;Johnstone ED;Sengers BG;Lewis RM;Glazier JD
系统L氨基酸底物在没有相反侧氨基酸（零反式摄取）的情况下进入离体胎盘质膜囊泡，这与氨基酸流入与流出相结合的强制性交换概念不相容。因此，我们假设系统L氨基酸交换转运体不是完全强制性的和/或氨基酸最初存在于囊泡内。为了解决这个问题，我们将计算模型与囊泡运输试验和转运体定位研究相结合，研究了介导[14C] L -丝氨酸（一种系统L底物）转运到人胎盘微绒毛质膜（MVM）囊泡中的机制。载体模型提供了一个定量框架来检验两种假设，即l-丝氨酸转运发生在强制性交换或非强制性交换加上促进运输（混合运输模型）。计算模型只能在转运体不完全处于交换模式时解释实验[14C]l-丝氨酸摄取数据，而交换模式最好由混合转运模型描述。MVM囊泡分离物含有内源性氨基酸，允许零反式摄取的潜在贡献。L系统的L型氨基酸转运体（lat1）和LAT2亚型均分布于MVM，其中L-丝氨酸转运归因于LAT2。这些发现表明，交换转运蛋白并不仅仅是义务交换蛋白。-Widdows, k.l., Panitchob， N., Crocker, i.p., Please, c.p., Hanson, m.a., Sibley, c.p., Johnstone, e.d., seners, b.g., Lewis, r.m., Glazier, j.d.将计算模型与膜转运研究相结合，揭示了对氨基酸交换转运机制的新见解。
Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [14C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [14C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms.
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影响因子：
3.5
作者：
Khunweeraphong N;Nagamori S;Wiriyasermkul P;Nishinaka Y;Wongthai P;Ohgaki R;Tanaka H;Tominaga H;Sakurai H;Kanai Y
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DOI：
10.1152/ajpcell.2000.278.6.c1162
发表时间：
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影响因子：
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影响因子：
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