Substrate specificity and kinetic parameters of GLUT3 in rat cerebellar granule neurons
Substrate specificity and kinetic parameters of GLUT3 in rat cerebellar granule neurons
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DOI：
10.1042/bj3150827
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发表时间：
1996-05-01
影响因子：
4.1
通讯作者：
Simpson, IA
中科院分区：
文献类型：
--
作者：
Maher, F;DaviesHill, TM;Simpson, IA
本研究探讨了表观亲和力，催化中心的活动（'营业额'）和立体特异性的神经元葡萄糖转运蛋白GLUT 3在原代培养小脑颗粒神经元。使用3-O-[C-14]甲基葡萄糖转运测定的新变体，通过在25 ℃下测量零反式动力学，确定GLUT 3是高表观亲和力、高活性的葡萄糖转运蛋白，K-m为2.87 +/- 0.23 mM（平均值+/- S.E.M.）对于3-O-甲基葡萄糖，V-max为18.7 +/- 0.48 nmol/min/10（6）个细胞，相应的催化中心活性为853 s（-1）。葡萄糖、甘露糖、2-脱氧葡萄糖和半乳糖竞争3-O-甲基葡萄糖的转运，而果糖不竞争。该方法与更常见的2-[H-3]脱氧葡萄糖方法和[U-C-14]葡萄糖转运方法进行了比较。神经元葡萄糖转运蛋白GLUT 3的高亲和力和转运活性似乎是一种适当的适应，以满足在主要的间质脑葡萄糖浓度（1-2 mM）下神经元代谢的需求。
This study examines the apparent affinity, catalytic-centre activity ('turnover number') and stereospecificity of the neuronal glucose transporter GLUT3 in primary cultured cerebellar granule neurons. Using a novel variation of the 3-O-[C-14]methylglucose transport assay, by measuring zero-trans kinetics at 25 degrees C, GLUT3 was determined to be a high-apparent-affinity, high-activity, glucose transporter with a K-m of 2.87 +/- 0.23 mM (mean +/- S.E.M.) for 3-O-methylglucose, a V-max of 18.7 +/- 0.48 nmol/min per 10(6) cells, and a corresponding catalytic-centre activity of 853 s(-1). Transport of 3-O-methylglucose was competed by glucose, mannose, 2-deoxyglucose and galactose, but not by fructose. This methodology is compared with the more common 2-[H-3]deoxyglucose methodology and the [U-C-14]glucose transport method. The high affinity and transport activity of the neuronal glucose transporter GLUT3 appears to be an appropriate adaptation to meet the demands of neuronal metabolism at prevailing interstitial brain glucose concentrations (1-2 mM).