Voit T, Patel K, Sewry C A, Strong P N, Dubowitz V, Dunn M J
Jerry Lewis Muscle Research Centre, Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London.
Monatsschr Kinderheilkd. 1989 Jan;137(1):20-7.
An RCA I-lectin binding glycoprotein of Mr = 370 kD is missing from or altered in the plasma membrane of Duchenne muscular dystrophy (DMD) skeletal muscle. In the present study the carbohydrate chain of this glycoprotein was localized to the external face of the plasma membrane in human skeletal muscle, and dystrophin, the protein product of the DMD gene, was localized to the inner (cytoplasmic) face. On double labelled Western blots the two proteins appeared as closely apposed but distinctly separate bands. Comparison of the plasma membrane binding of five lectins with overlapping sugar specificities in skeletal muscle from patients with DMD and the allelic milder disease form, Becker muscular dystrophy (BMD) showed that the RCA I-binding glycoprotein also strongly binds to phytohaemagglutinin, thereby largely characterising the carbohydrate binding site. This glycoprotein was absent or altered in DMD and markedly reduced in clinically manifest BMD but present in preclinical clinical BMD. There was no general depletion of plasma membrane glycoproteins in DMD because consistent plasma membrane binding could be demonstrated by peanut and maclura pomifera lectin. The possible implications of these findings for the pathogenesis of DMD/BMD are discussed.
杜兴氏肌营养不良症（DMD）骨骼肌的质膜中缺少或改变了一种相对分子质量为370 kD的蓖麻凝集素I（RCA I）结合糖蛋白。在本研究中，这种糖蛋白的糖链定位于人骨骼肌质膜的外表面，而DMD基因的蛋白质产物抗肌萎缩蛋白定位于内（细胞质）表面。在双重标记的蛋白质印迹上，这两种蛋白质表现为紧密相邻但明显分开的条带。比较DMD患者和等位基因较轻疾病形式贝克尔肌营养不良症（BMD）患者骨骼肌中具有重叠糖特异性的五种凝集素的质膜结合情况，结果表明，RCA I结合糖蛋白也能与植物血凝素强烈结合，从而在很大程度上确定了碳水化合物结合位点。这种糖蛋白在DMD中缺失或改变，在临床显性BMD中明显减少，但在临床前BMD中存在。DMD中不存在质膜糖蛋白的普遍耗竭，因为花生凝集素和桑科柘属凝集素可证明质膜存在持续结合。讨论了这些发现对DMD/BMD发病机制的可能影响。
