A stereospecific myo-inositol D-chiro-inositol transporter in HepG2 liver cells - Identification with D-chiro-[3-H-3]inositol
A stereospecific myo-inositol D-chiro-inositol transporter in HepG2 liver cells - Identification with D-chiro-[3-H-3]inositol
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DOI：
10.1074/jbc.271.17.10073
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发表时间：
1996-04-26
影响因子：
4.8
通讯作者：
Sherman, WR
中科院分区：
文献类型：
--
作者：
Ostlund, RE;Seemayer, R;Sherman, WR
d -氨基肌醇是肌醇的一种表聚体，存在于某些哺乳动物糖基磷脂酰肌醇蛋白锚点和具有胰岛素样生物活性的肌醇磷酸聚糖中。为了制备用于代谢研究的探针，采用硼三肽钠在pH 6.5条件下选择性还原D-chiro-3-肌糖合成D-chiro-[3-H-3]肌醇。D-chiro-[3-H-3]肌醇被HepG2人肝细胞通过饱和和立体特异性途径摄取，其中D-chiro-肌醇和肌醇平等竞争，但l -chiro-肌醇不被识别。d -葡萄糖，而不是l -葡萄糖，争夺D-chiro - [3-H-3]肌醇吸收葡萄糖的浓度4-28毫米。最大运输能力是717 pmol / mg细胞蛋白质/ 3 h的km值348μm .吸收降低了76%钠时消除介质和94%的实验时在0度前提下新的myo / D-chiro-inositol运输车是有别于sodium-myo-inositol co-transporter发现在许多组织和占所有的饱和D-chiro-inositol和吸收HepG2细胞可饱和低亲和力肌醇摄取的部分。它可能允许细胞在存在相对大量的肌肌醇竞争的情况下使用d -氨基肌醇。
D-chiro-Inositol is an epimer of myo-inositol that is found in certain mammalian glycosylphosphatidylinositol protein anchors and inositol phosphoglycans possessing insulin-like bioactivity. In order to generate a probe for metabolic studies, D-chiro-[3-H-3]inositol was synthesized by selective reduction of D-chiro-3-inosose at pH 6.5 with sodium borotritide. D-chiro-[3-H-3]Inositol was taken up by HepG2 human liver cells through a saturable and stereospecific pathway in which D-chiro-inositol and myo-inositol competed equally but L-chiro-inositol was not recognized. D-Glucose, but not L-glucose, competed for D-chiro-[3-H-3]inositol uptake over glucose concentrations of 4-28 mM. Maximum transport capacity was 717 pmol/mg cell protein/3 h with a K-m value of 348 mu M. Uptake was reduced by 76% when sodium was eliminated from the medium and by 94% when the experiment was performed at 0 degrees C.The new myo/D-chiro-inositol transporter is distinct from the sodium-myo-inositol co-transporter found in many tissues and accounts for all of the saturable D-chiro-inositol uptake and for a portion of the saturable low affinity myo-inositol uptake in HepG2 cells. It may allow D-chiro-inositol to be used by cells in the presence of a relatively large amount of competing myo-inositol.