Helmholtz Group Cell Biology, German Cancer Research Center, DKFZ, Heidelberg, Germany.
J Cell Mol Med. 2012 Aug;16(8):1709-19. doi: 10.1111/j.1582-4934.2011.01463.x.
Recently the protein myozap, a 54-kD polypeptide which is not a member of any of the known cytoskeletal and junctional protein multigene families, has been identified as a constituent of the plaques of the composite junctions in the intercalated disks connecting the cardiomyocytes of mammalian hearts. Using a set of novel, highly sensitive and specific antibodies we now report that myozap is also a major constituent of the cytoplasmic plaques of the adherens junctions (AJs) connecting the endothelial cells of the mammalian blood and lymph vascular systems, including the desmoplakin-containing complexus adhaerentes of the virgultar cells of lymph node sinus. In light and electron microscopic immunolocalization experiments we show that myozap colocalizes with several proteins of desmosomal plaques as well as with AJ-specific transmembrane molecules, including VE-cadherin. In biochemical analyses, rigorous immunoprecipitation experiments have revealed N-cadherin, desmoplakin, desmoglein-2, plakophilin-2, plakoglobin and plectin as very stably bound complex partners. We conclude that myozap is a general component of cell-cell junctions not only in the myocardium but also in diverse endothelia of the blood and lymph vascular systems of adult mammals, suggesting that this protein not only serves a specific role in the heart but also a broader set of functions in the vessel systems. We also propose to use myozap as an endothelial cell type marker in diagnoses.
最近，一种 54kD 的多肽蛋白 myozap 被鉴定为连接哺乳动物心肌细胞的闰盘复合连接处斑的组成部分，它不是任何已知细胞骨架和连接蛋白多基因家族的成员。使用一组新的、高度敏感和特异的抗体，我们现在报告 myozap 也是连接哺乳动物血液和淋巴血管系统内皮细胞的黏附连接（AJs）的细胞质斑的主要组成部分，包括淋巴结窦腔中的 Virgultar 细胞的含有 desmoplakin 的 complexus adhaerentes。在光镜和电镜免疫定位实验中，我们表明 myozap 与桥粒斑的几种蛋白以及 AJ 特异性跨膜分子，包括 VE-cadherin 共定位。在生化分析中，严格的免疫沉淀实验揭示了 N-钙黏蛋白、desmoplakin、desmoglein-2、 plakophilin-2、plakoglobin 和 plectin 作为非常稳定结合的复合物伙伴。我们得出结论，myozap 不仅是心肌细胞，而且也是成年哺乳动物血液和淋巴血管系统的各种内皮细胞的细胞-细胞连接的一般组成部分，这表明该蛋白不仅在心脏中具有特定作用，而且在血管系统中具有更广泛的作用。我们还提议使用 myozap 作为内皮细胞类型标志物用于诊断。
