Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Science. 2014 Apr 18;344(6181):304-7. doi: 10.1126/science.1248571.
Tight junctions are cell-cell adhesion structures in epithelial cell sheets that surround organ compartments in multicellular organisms and regulate the permeation of ions through the intercellular space. Claudins are the major constituents of tight junctions and form strands that mediate cell adhesion and function as paracellular barriers. We report the structure of mammalian claudin-15 at a resolution of 2.4 angstroms. The structure reveals a characteristic β-sheet fold comprising two extracellular segments, which is anchored to a transmembrane four-helix bundle by a consensus motif. Our analyses suggest potential paracellular pathways with distinctive charges on the extracellular surface, providing insight into the molecular basis of ion homeostasis across tight junctions.
紧密连接是多细胞生物中围绕器官隔室的上皮细胞片层中的细胞-细胞粘附结构，调节离子通过细胞间隙的渗透。 Claudins 是紧密连接的主要成分，形成介导细胞粘附的链，并作为细胞旁屏障发挥作用。我们报告了分辨率为 2.4 埃的哺乳动物 Claudin-15 的结构。该结构揭示了一种特征性的 β-折叠，由两个细胞外片段组成，通过共识基序锚定在跨膜四螺旋束上。我们的分析表明，细胞外表面具有独特的电荷，存在潜在的细胞旁途径，为离子通过紧密连接保持体内平衡的分子基础提供了深入了解。
