Ball E, Karlik C C, Beall C J, Saville D L, Sparrow J C, Bullard B, Fyrberg E A
Department of Biology, University of York, England.
Cell. 1987 Oct 23;51(2):221-8. doi: 10.1016/0092-8674(87)90149-8.
Flight muscles of some insects contain a myofibrillar protein termed arthrin, which is closely related to actin (mw 43,000). Here we demonstrate that arthrin (mw 55,000) is ubiquitinated actin. We show that in Act88FM342, a flightless Drosophila mutant wherein the Act88F actin gene specifies a glu93----lys replacement, isoelectric points of both actin III and arthrin are shifted, revealing that both are encoded by the same gene. Arthrin reacts with an anti-ubiquitin antibody, which demonstrates that its extra mass results from ubiquitin ligation. Approximately one-seventh of myofibrillar actin is stably ubiquitinated, suggesting that there may be one arthrin molecule per actin-tropomyosin-troponin cooperative unit. Arthrin formation lags several hours behind that of actin III, implying that ubiquitination coincides with some aspect of myofibril assembly.
一些昆虫的飞行肌肉含有一种名为节肢蛋白的肌原纤维蛋白，它与肌动蛋白（分子量43,000）密切相关。在此我们证明节肢蛋白（分子量55,000）是泛素化的肌动蛋白。我们表明，在Act88FM342（一种不能飞行的果蝇突变体，其中Act88F肌动蛋白基因指定了一个谷氨酸93到赖氨酸的替换）中，肌动蛋白III和节肢蛋白的等电点都发生了偏移，这表明两者由同一基因编码。节肢蛋白与抗泛素抗体发生反应，这表明其额外的质量是由泛素连接导致的。大约七分之一的肌原纤维肌动蛋白被稳定地泛素化，这表明每个肌动蛋白-原肌球蛋白-肌钙蛋白协同单位可能有一个节肢蛋白分子。节肢蛋白的形成比肌动蛋白III滞后几个小时，这意味着泛素化与肌原纤维组装的某些方面相吻合。
