Ohashi K, Ishikawa K, Maruyama K
Department of Biology, Faculty of Science, Chiba University.
J Biochem. 1988 Feb;103(2):367-9. doi: 10.1093/oxfordjournals.jbchem.a122275.
Ion-exchange column-purified I-protein was labeled by fluorescein isothiocyanate (FITC) at an equimolar ratio. When FITC-labeled I-protein was reacted with glycerinated myofibrils of chicken breast muscle in a phosphate-buffered saline, fluorescence was observed at the A-band and/or the Z-line of the sarcomere. However, FITC-labeled I-protein did not stain freshly prepared myofibrils. When FITC-I-protein was reacted with a nitrocellulose paper sheet on which muscle proteins were blotted after SDS-polyacrylamide gel electrophoresis, some peptide bands, including connectin and nebulin, were fluorescent. These facts can explain why anti-I-protein antibodies stain the A-I junctional region of fresh myofibrils and A-bands and/or Z-lines of glycerinated myofibrils. It is very likely that I-protein is transferred from the A-I junctions of myofibrils and translocates to A-bands and Z-lines, where some components that can bind to I-protein are localized, as myofibrils are degraded during the glycerination.
离子交换柱纯化的I蛋白与异硫氰酸荧光素（FITC）以等摩尔比进行标记。当FITC标记的I蛋白在磷酸盐缓冲盐水中与鸡胸肌甘油化肌原纤维反应时，在肌节的A带和/或Z线处观察到荧光。然而，FITC标记的I蛋白不会使新制备的肌原纤维染色。当FITC-I蛋白与在SDS-聚丙烯酰胺凝胶电泳后印迹了肌肉蛋白的硝酸纤维素纸片反应时，包括肌联蛋白和伴肌动蛋白在内的一些肽带发出荧光。这些事实可以解释为什么抗I蛋白抗体能够使新鲜肌原纤维的A-I连接区域以及甘油化肌原纤维的A带和/或Z线染色。很可能I蛋白从肌原纤维的A-I连接处转移并易位至A带和Z线，在甘油化过程中肌原纤维降解时，一些能够与I蛋白结合的成分定位于此处。
