Vemuri G S, Rao K V, Sastry P S
Department of Biochemistry, Indian Institute of Science, Bangalore.
Neurochem Res. 1994 Sep;19(9):1113-8. doi: 10.1007/BF00965143.
The topological disposition of Wolfgram proteins (WP) and their relationship with 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in human, rat, sheep, bovine, guinea pig and chicken CNS myelin was investigated. Controlled digestion of myelin with trypsin gave a 35KDa protein band (WP-t) when electrophoresed on dodecyl sulfate-polyacrylamide gel in all species. Western blot analysis showed that the WP-t was derived from WP. WP-t was also formed when rat myelin was treated with other proteases such as kallikrein, thermolysin and leucine aminopeptidase. Staining for CNPase activity on nitrocellulose blots showed that WP-t is enzymatically active. Much of the CNPase activity remained with the membrane fraction even after treatment with high concentrations of trypsin when WP were completely hydrolysed and no protein bands with M.W > 14KDa were detected on the gels. Therefore protein fragments of WP with M.W < 14KDa may contain CNPase activity. From these results, it is suggested that the topological disposition of all the various WP is such that a 35KDa fragment is embedded in the lipid bilayer and the remaining fragment exposed at the intraperiod line in the myelin structure which may play a role in the initiation of myelinogenesis.
研究了人、大鼠、绵羊、牛、豚鼠和鸡中枢神经系统髓鞘中沃尔夫格拉姆蛋白（WP）的拓扑分布及其与2',3'-环核苷酸3'-磷酸二酯酶（CNPase）的关系。用胰蛋白酶对髓鞘进行可控消化后，在十二烷基硫酸钠-聚丙烯酰胺凝胶上电泳，所有物种均出现一条35KDa的蛋白条带（WP-t）。蛋白质印迹分析表明，WP-t源自WP。用激肽释放酶、嗜热菌蛋白酶和亮氨酸氨肽酶等其他蛋白酶处理大鼠髓鞘时，也会形成WP-t。在硝酸纤维素膜上对CNPase活性进行染色显示，WP-t具有酶活性。即使在用高浓度胰蛋白酶处理后，当WP完全水解且凝胶上未检测到分子量>14KDa的蛋白条带时，大部分CNPase活性仍保留在膜部分。因此，分子量<14KDa的WP蛋白片段可能含有CNPase活性。从这些结果推测，所有不同WP的拓扑分布使得一个35KDa的片段嵌入脂质双层，其余片段暴露在髓鞘结构的周期内线，这可能在髓鞘形成起始过程中发挥作用。
