文昌鱼横纹肌中的肌动蛋白封端蛋白、CapZ（β-肌动蛋白结合蛋白）和原肌球蛋白。

Actin capping proteins, CapZ (β-actinin) and tropomodulin in amphioxus striated muscle.

机构信息

Department of Biology, Graduate School of Science, Chiba University, Chiba 263-8522, Japan.

出版信息

Gene. 2012 Nov 15;510(1):78-86. doi: 10.1016/j.gene.2012.07.081. Epub 2012 Aug 15.

DOI:10.1016/j.gene.2012.07.081

Abstract

CapZ (β-actinin) and tropomodulin (Tmod) are capping proteins involved in the maintenance of thin filaments in vertebrate skeletal muscles. In this study, we focused on amphioxus, the most primitive chordate. We searched for CapZ and Tmod genes in the amphioxus genome and determined their primary structures. Amphioxus possess one CapZα gene (CAPZA) and one CapZβ gene (CAPZB), and the transcripts of these genes were found to be 67%-85% identical to those of human CapZ genes. On the other hand, amphioxus contain one Tmod gene (TMOD), and the product of this gene has an identity of approximately 50% with human Tmod genes 1-4. However, helix 2 of amphioxus Tmod, which is involved in protein-binding to tropomyosin, was highly conserved with approximately 74% identity to human Tmod genes. Western blotting indicated the presence of CapZ and Tmod in the striated muscle of amphioxus. These results suggest that unlike most of vertebrates, such as fish, amphibian, bird, and mammal, CapZ from amphioxus striated muscle is derived from two genes CAPZA and CAPZB, and Tmod is derived from one TMOD gene.

摘要

肌球蛋白结合蛋白 CapZ（β-肌动蛋白）和原肌球蛋白帽蛋白 Tropomodulin（Tmod）在脊椎动物骨骼肌中维持细肌丝的稳定性方面发挥着重要作用。在本研究中，我们以文昌鱼为研究对象，文昌鱼是最原始的脊索动物。我们在文昌鱼基因组中搜索 CapZ 和 Tmod 基因，并确定了它们的一级结构。文昌鱼拥有一个 CapZα 基因（CAPZA）和一个 CapZβ 基因（CAPZB），这些基因的转录本与人类 CapZ 基因的相似度为 67%-85%。另一方面，文昌鱼含有一个 Tmod 基因（TMOD），该基因的产物与人类 Tmod 基因 1-4 的相似度约为 50%。然而，文昌鱼 Tmod 的螺旋 2 参与与原肌球蛋白的蛋白结合，与人类 Tmod 基因具有约 74%的高度同源性。Western blot 分析表明 CapZ 和 Tmod 存在于文昌鱼的横纹肌中。这些结果表明，与大多数脊椎动物（如鱼类、两栖类、鸟类和哺乳动物）不同，来自文昌鱼横纹肌的 CapZ 由两个基因 CAPZA 和 CAPZB 衍生而来，而 Tmod 由一个 TMOD 基因衍生而来。