葡萄糖转运蛋白4型

葡萄糖转运蛋白4型（英语：Glucose transporter type 4，简称GLUT4），也称为溶质载体家族2（solute carrier family 2）和促进葡萄糖转运蛋白成员4（facilitated glucose transporter member 4），是一种在人类中由SLC2A4基因编码的蛋白质。GLUT4是调节胰岛素的葡萄糖转运蛋白，主要存在于脂肪组织和横纹肌（骨骼肌和心脏）中。大卫·詹姆斯于1988年提供了这种独特的葡萄糖转运蛋白的第一个证据。编码GLUT4的基因于1989年被克隆和定位。 在细胞表面，GLUT4允许循环葡萄糖沿着其浓度梯度扩散到肌肉和脂肪细胞中。进入细胞后，葡萄糖被肝脏中的葡萄糖激酶和其他组织中的己糖激酶迅速磷酸化，形成葡萄糖-6-磷酸，然后进入糖酵解或聚合成糖原。葡萄糖-6-磷酸不能扩散回细胞外，这也有助于维持葡萄糖被动进入细胞的浓度梯度。 与所有蛋白质一样，GLUT4一级序列中独特的氨基酸排列使其能够跨质膜转运葡萄糖。除了N末端的苯丙氨酸外，COOH末端的两个亮氨酸残基和酸性基序被认为在胞吞作用和胞吐作用的动力学中起着关键作用。 根据序列相似性，共有14种葡萄糖转运蛋白（GLUT）分为3类。第1类包含GLUT1至4和14，第2类包含GLUT5、7、9和11，第3类包含GLUT6、8、10、12和13。 尽管所有葡萄糖转运蛋白之间存在一些序列差异，但它们都具有一些基本结构成分。例如，葡萄糖转运蛋白的N端和C端都暴露在细胞质中，它们都有12个跨膜片段。 在横纹骨骼肌细胞中，运动或肌肉收缩会增加质膜中的GLUT4浓度。 在运动过程中，身体需要将葡萄糖转化为ATP以用作能量。随着葡萄糖-6-磷酸浓度降低，己糖激酶受到的抑制减少，并且生成ATP的糖酵解和氧化途径能够继续进行。这也意味着随着细胞内浓度的降低，肌肉细胞能够吸收更多的葡萄糖。为了增加细胞中的葡萄糖水平，GLUT4是这种促进扩散中使用的初级转运蛋白。 尽管肌肉收缩以类似的方式发挥作用并且还诱导GLUT4易位到质膜中，但这两个骨骼肌过程获得不同形式的细胞内GLUT4。GLUT4载体囊泡为转铁蛋白阳性或阴性，并由不同的刺激物募集。阳性转铁蛋白GLUT4囊泡在肌肉收缩过程中被利用，而阴性转铁蛋白囊泡则被胰岛素刺激和运动激活。 心肌与骨骼肌略有不同。在休息时，他们更喜欢利用脂肪酸作为主要能量来源。随着活动的增加，它开始更快地泵血，心肌开始以更高的速度氧化葡萄糖。 对心肌中GLUT1和GLUT4的mRNA水平的分析表明，与在骨骼肌中相比，GLUT1在心肌中的作用更大。然而，GLUT4仍然被认为是葡萄糖的初级转运蛋白。 与其他组织非常相似，GLUT4也对胰岛素信号作出反应，并被转运到质膜中以促进葡萄糖扩散到细胞中。 脂肪组织是能量的储存库，以保持代谢稳态。当身体以葡萄糖的形式吸收能量时，一些会被消耗掉，其余的会以糖原的形式储存（主要在肝脏、肌肉细胞中），或在脂肪组织中以甘油三酯的形式储存。 葡萄糖的摄入和能量消耗的不平衡已被证明会导致脂肪细胞肥大和增生，从而导致肥胖。此外，脂肪细胞中GLUT4基因的突变也会导致脂肪细胞中GLUT4表达增加，从而增加葡萄糖摄取，从而储存更多脂肪。如果GLUT4过度表达，它实际上会改变营养分配并将过量的葡萄糖输送到脂肪组织中，从而导致脂肪组织质量增加。 随着血液中葡萄糖浓度的增加，胰岛素从胰腺释放并进入血流。胰岛素储存在胰腺的胰岛β细胞中。当血液中的葡萄糖与胰岛β细胞膜上的葡萄糖受体结合时，信号级联会在细胞内启动，导致储存在这些细胞的囊泡中的胰岛素被释放到血流中。胰岛素水平升高导致细胞吸收葡萄糖。GLUT4储存在细胞的运输囊泡中，当胰岛素与膜受体结合时，它会迅速掺入细胞的质膜中。 在低胰岛素条件下，大多数GLUT4被隔离在肌肉和脂肪细胞的细胞内囊泡中。当囊泡与质膜融合时，GLUT4转运蛋白被插入并可用于转运葡萄糖以及葡萄糖吸收增加。基因工程肌肉胰岛素受体敲除（MIRKO）小鼠被设计为对胰岛素引起的葡萄糖摄取不敏感，这意味着GLUT4不存在。然而，发现患有糖尿病或空腹高血糖症的小鼠对不敏感的负面影响具有免疫力。 GLUT4的机制是级联效应的一个例子，其中配体与膜受体的结合会放大信号并引起细胞反应。在这种情况下，胰岛素以二聚体形式与胰岛素受体结合并激活受体的酪氨酸激酶结构域。然后受体募集胰岛素受体底物1（IRS1），它结合磷酸肌醇3-激酶。磷酸肌醇3-激酶将膜脂PIP2转化为PIP3。PIP3被蛋白激酶B和PDK1特别识别，PDK1可以磷酸化并激活PKB。磷酸化后，PKB处于活性形式并磷酸化TBC1D4，从而抑制与TBC1D4相关的三磷酸鸟苷酶激活结构域，从而使Rab蛋白从其二磷酸鸟苷变为三磷酸鸟苷结合状态。三磷酸鸟苷酶激活结构域的抑制使级联中的下一个蛋白质以其活性形式存在，并刺激GLUT4在质膜上表达。 RAC1是一种三磷酸鸟苷，也被胰岛素激活。Rac1刺激皮质肌动蛋白细胞骨架的重组，从而允许GLUT4囊泡插入质膜。RAC1基因敲除小鼠肌肉组织中的葡萄糖摄取减少。 GLUT4杂合子基因敲除小鼠的肌肉会出现胰岛素抵抗以及糖尿病。 肌肉收缩刺激肌肉细胞将GLUT4受体转移到它们的表面。在心肌中尤其如此，连续收缩会增加GLUT4易位率；但在较小程度上观察到骨骼肌收缩增加。在骨骼肌中，肌肉收缩使GLUT4易位增加数倍，这可能受RAC1和一磷酸腺苷活化蛋白激酶的调节。 肌肉拉伸还通过RAC1刺激啮齿动物肌肉中的GLUT4易位和葡萄糖摄取。 GLUT4已被证明与死亡相关蛋白6（也称为Daxx）相互作用。用于调节细胞凋亡的Daxx已被证明与细胞质中的GLUT4相关。UBX结构域，例如在GLUT4中发现的结构域，已被证明与凋亡信号有关。因此，这种相互作用有助于Daxx在细胞内的易位。 此外，最近的报道表明在海马体等中枢神经系统中存在GLUT4基因。此外，海马体中胰岛素刺激的GLUT4运输受损导致海马体神经元的代谢活动和可塑性降低，从而导致抑郁样行为和认知功能障碍。 Template:GlycolysisGluconeogenesis WP534 James DE, Brown R, Navarro J, Pilch PF. Insulin-regulatable tissues express a unique insulin-sensitive glucose transport protein. Nature. May 1988, 333 (6169): 183–5. Bibcode:1988Natur.333..183J. PMID 3285221. S2CID 4237493. doi:10.1038/333183a0.  James DE, Strube M, Mueckler M. Molecular cloning and characterization of an insulin-regulatable glucose transporter. Nature. March 1989, 338 (6210): 83–7. Bibcode:1989Natur.338...83J. PMID 2645527. S2CID 4285627. doi:10.1038/338083a0.  Birnbaum MJ. Identification of a novel gene encoding an insulin-responsive glucose transporter protein. Cell. April 1989, 57 (2): 305–15. PMID 2649253. S2CID 20359706. doi:10.1016/0092-8674(89)90968-9.  Bell GI, Murray JC, Nakamura Y, Kayano T, Eddy RL, Fan YS, Byers MG, Shows TB. Polymorphic human insulin-responsive glucose-transporter gene on chromosome 17p13. Diabetes. August 1989, 38 (8): 1072–5. PMID 2568955. doi:10.2337/diabetes.38.8.1072.  Watson RT, Kanzaki M, Pessin JE. Regulated membrane trafficking of the insulin-responsive glucose transporter 4 in adipocytes. Endocrine Reviews. April 2004, 25 (2): 177–204. PMID 15082519. doi:10.1210/er.2003-0011 .  Buchberger A, Howard MJ, Proctor M, Bycroft M. The UBX domain: a widespread ubiquitin-like module. Journal of Molecular Biology. March 2001, 307 (1): 17–24. PMID 11243799. doi:10.1006/jmbi.2000.4462.  Huang S, Czech MP. The GLUT4 glucose transporter. Cell Metabolism. April 2007, 5 (4): 237–52. PMID 17403369. doi:10.1016/j.cmet.2007.03.006 .  Mueckler M, Thorens B. The SLC2 (GLUT) family of membrane transporters. Molecular Aspects of Medicine. 2013, 34 (2–3): 121–38. PMC 4104978 . PMID 23506862. doi:10.1016/j.mam.2012.07.001.  Lodish H, Berk A, Zipursky SL, Matsudaira P, Baltimore D, Darnell J. 16.1: Oxidation of Glucose and Fatty Acids to CO2. Molecular Cell Biology 4th. New York: W. H. Freeman. 2000. ISBN 978-0-7167-3706-3.  含有內容需登入查看的頁面 (link) Richter EA, Hargreaves M. Exercise, GLUT4, and skeletal muscle glucose uptake. Physiological Reviews. July 2013, 93 (3): 993–1017. PMID 23899560. doi:10.1152/physrev.00038.2012 （英语）.  Ploug T, van Deurs B, Ai H, Cushman SW, Ralston E. Analysis of GLUT4 distribution in whole skeletal muscle fibers: identification of distinct storage compartments that are recruited by insulin and muscle contractions. The Journal of Cell Biology. September 1998, 142 (6): 1429–46. PMC 2141761 . PMID 9744875. doi:10.1083/jcb.142.6.1429 （英语）.  Lauritzen HP. Insulin- and contraction-induced glucose transporter 4 traffic in muscle: insights from a novel imaging approach. Exercise and Sport Sciences Reviews. April 2013, 41 (2): 77–86. PMC 3602324 . PMID 23072821. doi:10.1097/JES.0b013e318275574c.  Morgan HE, Henderson MJ, Regen DM, Park CR. Regulation of glucose uptake in heart muscle from normal and alloxan-diabetic rats: the effects of insulin, growth hormone, cortisone, and anoxia. Annals of the New York Academy of Sciences. September 1959, 82 (2): 387–402. Bibcode:1959NYASA..82..387M. PMID 14424107. S2CID 32458568. doi:10.1111/j.1749-6632.1959.tb44920.x.  Laybutt DR, Thompson AL, Cooney GJ, Kraegen EW. Selective chronic regulation of GLUT1 and GLUT4 content by insulin, glucose, and lipid in rat cardiac muscle in vivo. The American Journal of Physiology. September 1997, 273 (3 Pt 2): H1309–16. PMID 9321820. doi:10.1152/ajpheart.1997.273.3.H1309 （英语）.  Rett K, Wicklmayr M, Dietze GJ, Häring HU. Insulin-induced glucose transporter (GLUT1 and GLUT4) translocation in cardiac muscle tissue is mimicked by bradykinin. Diabetes. January 1996,. 45 Suppl 1 (Supplement 1): S66–9. PMID 8529803. S2CID 7766813. doi:10.2337/diab.45.1.S66 （英语）.  Slot JW, Geuze HJ, Gigengack S, James DE, Lienhard GE. Translocation of the glucose transporter GLUT4 in cardiac myocytes of the rat. Proceedings of the National Academy of Sciences of the United States of America. September 1991, 88 (17): 7815–9. Bibcode:1991PNAS...88.7815S. PMC 52394 . PMID 1881917. doi:10.1073/pnas.88.17.7815  （英语）.  Luiken JJ, Glatz JF, Neumann D. Cardiac contraction-induced GLUT4 translocation requires dual signaling input (PDF). Trends Endocrinol Metab. August 2015, 26 (8): 404–10 [2022-12-10]. PMID 26138758. S2CID 171571. doi:10.1016/j.tem.2015.06.002. （原始内容存档 (PDF)于2022-12-04）.  Favaretto F, Milan G, Collin GB, Marshall JD, Stasi F, Maffei P, Vettor R, Naggert JK. GLUT4 defects in adipose tissue are early signs of metabolic alterations in Alms1GT/GT, a mouse model for obesity and insulin resistance. PLOS ONE. 2014-10-09, 9 (10): e109540. Bibcode:2014PLoSO...9j9540F. PMC 4192353 . PMID 25299671. doi:10.1371/journal.pone.0109540 .  Shepherd PR, Gnudi L, Tozzo E, Yang H, Leach F, Kahn BB. Adipose cell hyperplasia and enhanced glucose disposal in transgenic mice overexpressing GLUT4 selectively in adipose tissue. The Journal of Biological Chemistry. October 1993, 268 (30): 22243–6. PMID 8226728. doi:10.1016/S0021-9258(18)41516-5 .  Insulin Synthesis and Secretion. www.vivo.colostate.edu. [2017-05-24]. （原始内容存档于2022-12-04）.  Fu, Zhuo. Regulation of Insulin Synthesis and Secretion and Pancreatic Beta-Cell Dysfunction in Diabetes. Curr Diabetes Rev. 2013, 9 (1): 25–53. PMC 3934755 . PMID 22974359. doi:10.2174/1573399811309010025.  Cushman SW, Wardzala LJ. Potential mechanism of insulin action on glucose transport in the isolated rat adipose cell. Apparent translocation of intracellular transport systems to the plasma membrane (PDF). The Journal of Biological Chemistry. May 1980, 255 (10): 4758–62 [2022-12-10]. PMID 6989818. doi:10.1016/S0021-9258(19)85561-8 . （原始内容存档 (PDF)于2017-05-17）.  Sonksen P, Sonksen J. Insulin: understanding its action in health and disease. British Journal of Anaesthesia. July 2000, 85 (1): 69–79. PMID 10927996. doi:10.1093/bja/85.1.69  （英语）.  Leto, Dara; Saltiel, Alan R. Regulation of glucose transport by insulin: traffic control of GLUT4. Nature Reviews Molecular Cell Biology. May 2012, 13 (6): 383–396. ISSN 1471-0072. PMID 22617471. S2CID 39756994. doi:10.1038/nrm3351 （英语）.  JeBailey L, Wanono O, Niu W, Roessler J, Rudich A, Klip A. Ceramide- and oxidant-induced insulin resistance involve loss of insulin-dependent Rac-activation and actin remodeling in muscle cells. Diabetes. February 2007, 56 (2): 394–403. PMID 17259384. doi:10.2337/db06-0823 .  Sylow L, Kleinert M, Pehmøller C, Prats C, Chiu TT, Klip A, Richter EA, Jensen TE. Akt and Rac1 signaling are jointly required for insulin-stimulated glucose uptake in skeletal muscle and downregulated in insulin resistance. Cellular Signalling. February 2014, 26 (2): 323–31. PMID 24216610. doi:10.1016/j.cellsig.2013.11.007.  Sylow L, Jensen TE, Kleinert M, Højlund K, Kiens B, Wojtaszewski J, Prats C, Schjerling P, Richter EA. Rac1 signaling is required for insulin-stimulated glucose uptake and is dysregulated in insulin-resistant murine and human skeletal muscle. Diabetes. June 2013, 62 (6): 1865–75. PMC 3661612 . PMID 23423567. doi:10.2337/db12-1148.  Stenbit AE, Tsao TS, Li J, Burcelin R, Geenen DL, Factor SM, Houseknecht K, Katz EB, Charron MJ. GLUT4 heterozygous knockout mice develop muscle insulin resistance and diabetes. Nature Medicine. October 1997, 3 (10): 1096–101. PMID 9334720. S2CID 8643507. doi:10.1038/nm1097-1096.  Lund S, Holman GD, Schmitz O, Pedersen O. Contraction stimulates translocation of glucose transporter GLUT4 in skeletal muscle through a mechanism distinct from that of insulin. Proceedings of the National Academy of Sciences of the United States of America. June 1995, 92 (13): 5817–21. Bibcode:1995PNAS...92.5817L. PMC 41592 . PMID 7597034. doi:10.1073/pnas.92.13.5817 .  Jensen TE, Sylow L, Rose AJ, Madsen AB, Angin Y, Maarbjerg SJ, Richter EA. Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca(2+) release. Molecular Metabolism. October 2014, 3 (7): 742–53. PMC 4209358 . PMID 25353002. doi:10.1016/j.molmet.2014.07.005.  Sylow L, Møller LL, Kleinert M, Richter EA, Jensen TE. Rac1--a novel regulator of contraction-stimulated glucose uptake in skeletal muscle. Experimental Physiology. December 2014, 99 (12): 1574–80. PMID 25239922. doi:10.1113/expphysiol.2014.079194 .  Sylow L, Jensen TE, Kleinert M, Mouatt JR, Maarbjerg SJ, Jeppesen J, Prats C, Chiu TT, Boguslavsky S, Klip A, Schjerling P, Richter EA. Rac1 is a novel regulator of contraction-stimulated glucose uptake in skeletal muscle. Diabetes. April 2013, 62 (4): 1139–51. PMC 3609592 . PMID 23274900. doi:10.2337/db12-0491.  Mu J, Brozinick JT, Valladares O, Bucan M, Birnbaum MJ. A role for AMP-activated protein kinase in contraction- and hypoxia-regulated glucose transport in skeletal muscle. Molecular Cell. May 2001, 7 (5): 1085–94. PMID 11389854. doi:10.1016/s1097-2765(01)00251-9 .  Sylow L, Møller LL, Kleinert M, Richter EA, Jensen TE. Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1. The Journal of Physiology. February 2015, 593 (3): 645–56. PMC 4324711 . PMID 25416624. doi:10.1113/jphysiol.2014.284281.  引用错误：没有为名为Buchberger_2001的参考文献提供内容 Lalioti VS, Vergarajauregui S, Pulido D, Sandoval IV. The insulin-sensitive glucose transporter, GLUT4, interacts physically with Daxx. Two proteins with capacity to bind Ubc9 and conjugated to SUMO1. The Journal of Biological Chemistry. May 2002, 277 (22): 19783–91. PMID 11842083. doi:10.1074/jbc.M110294200 .  Patel SS, Udayabanu M. Urtica dioica extract attenuates depressive like behavior and associative memory dysfunction in dexamethasone induced diabetic mice. Metabolic Brain Disease. March 2014, 29 (1): 121–30. PMID 24435938. S2CID 10955351. doi:10.1007/s11011-014-9480-0.  Piroli GG, Grillo CA, Reznikov LR, Adams S, McEwen BS, Charron MJ, Reagan LP. Corticosterone impairs insulin-stimulated translocation of GLUT4 in the rat hippocampus. Neuroendocrinology. 2007, 85 (2): 71–80. PMID 17426391. S2CID 38081413. doi:10.1159/000101694.  Huang CC, Lee CC, Hsu KS. The role of insulin receptor signaling in synaptic plasticity and cognitive function. Chang Gung Medical Journal. 2010, 33 (2): 115–25. PMID 20438663.  醫學主題詞表（MeSH）：GLUT4+Protein USCD—Nature molecule pages: The signaling pathway", "GLUT4"; contains a high-resolution network map. Accessed 25 December 2009.