Agrin binding to alpha-dystroglycan. Domains of agrin necessary to induce acetylcholine receptor clustering are overlapping but not identical to the alpha-dystroglycan-binding region.
Agrin binding to alpha-dystroglycan. Domains of agrin necessary to induce acetylcholine receptor clustering are overlapping but not identical to the alpha-dystroglycan-binding region.
复制标题
集聚蛋白与 α-肌营养不良聚糖结合。
DOI：
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复制
发表时间：
1996
影响因子：
4.8
通讯作者：
W. Hoch
中科院分区：
文献类型：
--
作者：
C. Hopf;W. Hoch
The synaptic basal membrane protein agrin initiates the aggregation of acetylcholine receptors at the postsynaptic membrane of the developing neuromuscular junction. Recently, alpha-dystroglycan was found to be a major agrin-binding protein on the muscle cell surface and was therefore considered a candidate agrin receptor. Employing different truncation fragments of agrin, we determined regions of the protein involved in binding to alpha-dystroglycan and to heparin, an inhibitor of alpha-dystroglycan binding. Deletion of a 15-kDa fragment from the C terminus of agrin had no effect on its binding to alpha-dystroglycan from rabbit muscle membranes, even though this deletion completely abolishes its acetylcholine receptor aggregating activity. Conversely, deletion of a central region does not affect agrin's clustering activity, but reduced its affinity for alpha-dystroglycan. Combination of these two deletions resulted in a fragment of approximately 35 kDa that weakly bound to alpha-dystroglycan, but displayed no clustering activity. All of these fragments bound to heparin with high affinity. Thus, alpha-dystroglycan does not show the binding specificity expected for an agrin receptor. Our data suggest the existence of an additional component on the muscle cell surface that generates the observed ligand specificity.
