Atomi Y, Yamada S, Strohman R, Nonomura Y
Department of Sports Sciences, College of Arts & Sciences, University of Tokyo.
J Biochem. 1991 Nov;110(5):812-22. doi: 10.1093/oxfordjournals.jbchem.a123665.
Atrophy of rat soleus muscles by hindlimb suspension is characterized by an early dramatic decrease in a soluble 22-kDa protein. The 22-kDa protein was purified from rat red skeletal muscle and rat lens by three different methods of chromatography. The partial amino acid sequence (65% of total amino acids) determined for muscle 22-kDa protein was identical with that of rat lens crystallin. The HPLC elution patterns of lysylendopeptidase fragments of 22-kDa protein from the two sources were identical. Polyclonal antibodies to rat muscle and bovine lens alpha B-crystallin with the two proteins on immunoblotting. alpha B-Crystallin protein was expressed and synthesized efficiently in slow skeletal muscle and poorly in fast muscle. Thus, the decreased 22-kDa protein of slow muscle in the suspension treatment was confirmed to be alpha B-crystallin. Immunoblotting confirmed that most of the alpha B-crystallin was solubilized, though some was tightly bound to myofibrils. This bound portion was localized in Z-bands of isolated myofibrils by immunocytochemical light and electron microscopy. Muscle alpha B-crystallin is tentatively proposed to be a myofibril-stabilizing protein, based upon its extraction characteristics, localization, and amino acid sequence.
后肢悬吊导致的大鼠比目鱼肌萎缩的特征是一种可溶性22 kDa蛋白早期显著减少。通过三种不同的色谱方法从大鼠红色骨骼肌和大鼠晶状体中纯化出了这种22 kDa蛋白。测定的肌肉22 kDa蛋白的部分氨基酸序列（占总氨基酸的65%）与大鼠晶状体结晶蛋白的序列相同。来自这两种来源的22 kDa蛋白的赖氨酰内肽酶片段的高效液相色谱洗脱模式相同。用针对大鼠肌肉和牛晶状体αB-晶状体蛋白的多克隆抗体对这两种蛋白进行免疫印迹分析。αB-晶状体蛋白在慢肌中高效表达和合成，在快肌中则表达较差。因此，证实悬吊处理后慢肌中减少的22 kDa蛋白为αB-晶状体蛋白。免疫印迹证实，大部分αB-晶状体蛋白被溶解，尽管有一些与肌原纤维紧密结合。通过免疫细胞化学光镜和电镜观察，这种结合部分定位于分离的肌原纤维的Z带。基于其提取特性、定位和氨基酸序列，初步推测肌肉αB-晶状体蛋白是一种肌原纤维稳定蛋白。
