Desjardins L M, Sanwal B D, Ball E H
Department of Biochemistry, University of Western Ontario, London.
Exp Cell Res. 1994 Aug;213(2):327-34. doi: 10.1006/excr.1994.1206.
A monoclonal antibody generated from a mouse immunized with L6 rat myoblast cells was found to react with a major 700-kDa band and a minor 500-kDa band in immunoblots. Immunofluorescence microscopy demonstrated a submembranous location in tissue sections and an exclusion from stress fiber regions in cultured cells. Further, permeabilization of cultured cells with nonionic detergent prior to fixation changed the diffuse pattern of fluorescence to a web. These findings are characteristic of membrane skeletal proteins. In muscle tissue, the protein was much more abundant in fast twitch fibers and was found in internal locations as well as at the membrane. The protein could be solubilized in the absence of detergents and, hence, is not transmembrane. Although initially discovered in myoblast cells, the protein is present in a variety of tissue types, including brain, kidney, heart, liver, and lung. Pulse-chase labeling of the two bands suggested that the 500-kDa band was not a breakdown product of the 700-kDa protein. The protein appears to be a previously undiscovered membrane skeletal constituent for which the name "endossin" is proposed.
用L6大鼠成肌细胞免疫小鼠产生的一种单克隆抗体，在免疫印迹中被发现可与一条主要的700 kDa条带和一条次要的500 kDa条带发生反应。免疫荧光显微镜检查显示，在组织切片中该蛋白位于膜下，在培养细胞中则排除在应力纤维区域之外。此外，在固定之前用非离子去污剂使培养细胞通透化，会使荧光的弥散模式变为网状。这些发现是膜骨架蛋白的特征。在肌肉组织中，该蛋白在快肌纤维中含量丰富得多，并且在内部位置以及膜处均有发现。该蛋白可以在没有去污剂的情况下溶解，因此不是跨膜蛋白。尽管最初是在成肌细胞中发现的，但该蛋白存在于多种组织类型中，包括脑、肾、心、肝和肺。对这两条带进行脉冲追踪标记表明，500 kDa条带不是700 kDa蛋白的降解产物。该蛋白似乎是一种先前未被发现的膜骨架成分，为此提议将其命名为“内骨素”。
