Kobayashi R, Itoh H, Tashima Y
Department of Biochemistry, Akita University School of Medicine, Japan.
Eur J Biochem. 1989 Nov 6;185(2):297-302. doi: 10.1111/j.1432-1033.1989.tb15115.x.
The isoforms of skeletal muscle alpha-actinin present during chick embryogenesis were analyzed by two-dimensional electrophoresis in combination with the immunoblot technique. Chicken embryonic muscles at 8-15 days contain an embryo-specific isoform of alpha-actinin. The embryonic alpha-actinin isoform has a molecular mass of 112 kDa and an isoelectric point of 5.8, whereas the values for the adult isoform of alpha-actinin were 100 kDa and 5.85, respectively. To characterize the two classes of alpha-actinin polypeptides we have compared the two proteins by 125I-labeled two-dimensional peptide mapping. The embryonic isoform is highly similar to, but exhibited extensive peptide differences to, the adult isoform of alpha-actinin. The developmental sequence of the expression of the alpha-actinins was also studied. In extracts of skeletal muscle from 8-10-day-old embryos, only the embryonic isoform was detected. In extracts from 15-day-old embryos, both the embryonic and the adult isoforms coexisted. However by 21 days, the embryonic isoform had disappeared and only the adult isoform was detected. These data suggested that the embryonic and the adult isoform of alpha-actinins are distinct proteins and that during skeletal myogenesis in ovo one class of alpha-actinin is replaced by a new class of alpha-actinin polypeptides, and that the latter is maintained into adulthood.
采用二维电泳结合免疫印迹技术分析了鸡胚胎发育过程中骨骼肌α-辅肌动蛋白的同工型。8至15日龄的鸡胚胎肌肉中含有一种胚胎特异性的α-辅肌动蛋白同工型。胚胎α-辅肌动蛋白同工型的分子量为112 kDa，等电点为5.8，而成人α-辅肌动蛋白同工型的值分别为100 kDa和5.85。为了表征这两类α-辅肌动蛋白多肽，我们通过125I标记的二维肽图对这两种蛋白质进行了比较。胚胎同工型与成人α-辅肌动蛋白同工型高度相似，但也表现出广泛的肽差异。还研究了α-辅肌动蛋白表达的发育序列。在8至10日龄胚胎的骨骼肌提取物中，仅检测到胚胎同工型。在15日龄胚胎的提取物中，胚胎同工型和成人同工型共存。然而，到21天时，胚胎同工型已经消失，仅检测到成人同工型。这些数据表明，α-辅肌动蛋白的胚胎同工型和成人同工型是不同的蛋白质，并且在鸡胚骨骼肌生成过程中，一类α-辅肌动蛋白被一类新的α-辅肌动蛋白多肽所取代，并且后者一直维持到成年期。
