Zhou D, Ursitti J A, Bloch R J
Department of Physiology, University of Maryland School of Medicine, Baltimore 21201, USA.
Mol Biol Cell. 1998 Jan;9(1):47-61. doi: 10.1091/mbc.9.1.47.
Skeletal muscle contains spectrin (or spectrin I) and fodrin (or spectrin II), members of the spectrin supergene family. We used isoform-specific antibodies and cDNA probes to investigate the molecular forms, developmental expression, and subcellular localization of the spectrins in skeletal muscle of the rat. We report that beta-spectrin (betaI) replaces beta-fodrin (betaII) at the sarcolemma as skeletal muscle fibers develop. As a result, adult muscle fibers contain only alpha-fodrin (alphaII) and the muscle isoform of beta-spectrin (betaISigma2). By contrast, other types of cells present in skeletal muscle tissue, including blood vessels and nerves, contain only alpha- and beta-fodrin. During late embryogenesis and early postnatal development, skeletal muscle fibers contain a previously unknown form of spectrin complex, consisting of alpha-fodrin, beta-fodrin, and the muscle isoform of beta-spectrin. These complexes associate with the sarcolemma to form linear membrane skeletal structures that otherwise resemble the structures found in the adult. Our results suggest that the spectrin-based membrane skeleton of muscle fibers can exist in three distinct states during development.
骨骼肌含有血影蛋白(或血影蛋白I)和肌动蛋白(或血影蛋白II),它们是血影蛋白超基因家族的成员。我们使用同工型特异性抗体和cDNA探针来研究大鼠骨骼肌中血影蛋白的分子形式、发育表达和亚细胞定位。我们报告说,随着骨骼肌纤维的发育,β-血影蛋白(βI)在肌膜处取代了β-肌动蛋白(βII)。因此,成年肌纤维仅含有α-肌动蛋白(αII)和β-血影蛋白的肌肉同工型(βISigma2)。相比之下,骨骼肌组织中存在的其他类型细胞,包括血管和神经,仅含有α-和β-肌动蛋白。在胚胎发育后期和出生后早期发育阶段,骨骼肌纤维含有一种以前未知的血影蛋白复合物形式,由α-肌动蛋白、β-肌动蛋白和β-血影蛋白的肌肉同工型组成。这些复合物与肌膜结合形成线性膜骨架结构,否则类似于在成年个体中发现的结构。我们的结果表明,肌纤维基于血影蛋白的膜骨架在发育过程中可以存在三种不同状态。