A role for the dystrophin-glycoprotein complex as a transmembrane linker between laminin and actin.
A role for the dystrophin-glycoprotein complex as a transmembrane linker between laminin and actin.
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DOI：
10.1083/jcb.122.4.809
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发表时间：
1993-08
期刊：
影响因子：
--
通讯作者：
Campbell KP
中科院分区：
文献类型：
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作者：
Ervasti JM;Campbell KP
肌营养不良蛋白-糖蛋白复合物与细胞外基质以及肌动蛋白的几种组分进行了相互作用的测试。156-kD抗肌萎缩蛋白相关糖蛋白（156-kD抗肌萎缩蛋白聚糖）以钙依赖性方式特异性结合层粘连蛋白，并被NaCl抑制（IC 50 = 250 mM），但不受1,000倍（wt/wt）过量乳糖、IKVAV或YIGSR肽的影响。层粘连蛋白结合被肝素抑制（IC 50 = 100微克/毫升），表明层粘连蛋白的肝素结合域之一参与结合肌营养不良蛋白聚糖，而肌营养不良蛋白聚糖上的带负电荷的寡糖部分被发现是其层粘连蛋白结合活性所必需的。肌营养不良蛋白-糖蛋白复合物的任何组分与纤连蛋白、胶原I、胶原IV、巢蛋白或硫酸乙酰肝素蛋白聚糖之间没有相互作用，通过125 I-蛋白覆盖和/或细胞外基质蛋白-琼脂糖沉淀检测。此外，层粘连蛋白-琼脂糖凝胶定量沉淀纯化的肌营养不良蛋白-糖蛋白复合物，表明当肌营养不良蛋白聚糖与复合物结合时，层粘连蛋白结合位点是可接近的。非肌肉组织的肌营养不良聚糖也结合层粘连蛋白。然而，横纹肌肌营养不良蛋白-糖蛋白复合物的其他蛋白质似乎是不存在的，抗原性不同或不太紧密相关的非肌肉组织中的肌营养不良蛋白聚糖。最后，我们表明，肌营养不良蛋白-糖蛋白复合物与F-肌动蛋白共沉积，但不结合钙或钙调蛋白。我们的研究结果支持横纹肌肌营养不良蛋白-糖蛋白复合物在连接肌动蛋白为基础的细胞骨架与细胞外基质的作用。此外，我们的研究结果表明，肌营养不良蛋白和dystroglycan可能发挥实质上不同的功能在非肌肉组织中的作用。
The dystrophin-glycoprotein complex was tested for interaction with several components of the extracellular matrix as well as actin. The 156-kD dystrophin-associated glycoprotein (156-kD dystroglycan) specifically bound laminin in a calcium-dependent manner and was inhibited by NaCl (IC50 = 250 mM) but was not affected by 1,000-fold (wt/wt) excesses of lactose, IKVAV, or YIGSR peptides. Laminin binding was inhibited by heparin (IC50 = 100 micrograms/ml), suggesting that one of the heparin-binding domains of laminin is involved in binding dystroglycan while negatively charged oligosaccharide moieties on dystroglycan were found to be necessary for its laminin-binding activity. No interaction between any component of the dystrophin- glycoprotein complex and fibronectin, collagen I, collagen IV, entactin, or heparan sulfate proteoglycan was detected by 125I-protein overlay and/or extracellular matrix protein-Sepharose precipitation. In addition, laminin-Sepharose quantitatively precipitated purified dystrophin-glycoprotein complex, demonstrating that the laminin-binding site is accessible when dystroglycan is associated with the complex. Dystroglycan of nonmuscle tissues also bound laminin. However, the other proteins of the striated muscle dystrophin-glycoprotein complex appear to be absent, antigenically dissimilar or less tightly associated with dystroglycan in nonmuscle tissues. Finally, we show that the dystrophin-glycoprotein complex cosediments with F-actin but does not bind calcium or calmodulin. Our results support a role for the striated muscle dystrophin-glycoprotein complex in linking the actin- based cytoskeleton with the extracellular matrix. Furthermore, our results suggest that dystrophin and dystroglycan may play substantially different functional roles in nonmuscle tissues.