Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, 6312 MBRB, Chapel Hill, North Carolina 27599-7545, USA.
Cold Spring Harb Perspect Biol. 2009 Aug;1(2):a002584. doi: 10.1101/cshperspect.a002584.
Understanding of tight junctions has evolved from their historical perception as inert solute barriers to recognition of their physiological and biochemical complexity. Many proteins are specifically localized to tight junctions, including cytoplasmic actin-binding proteins and adhesive transmembrane proteins. Among the latter are claudins, which are critical barrier proteins. Current information suggests that the paracellular barrier is most usefully modeled as having two physiologic components: a system of charge-selective small pores, 4 A in radius, and a second pathway created by larger discontinuities in the barrier, lacking charge or size discrimination. The first pathway is influenced by claudin expression patterns and the second is likely controlled by different proteins and signals. Recent information on claudin function and disease-causing mutations have led to a more complete understanding of their role in barrier formation, but progress is impeded by lack of high resolution structural information.
对紧密连接的认识已经从其作为惰性溶质屏障的历史观念演变为对其生理和生化复杂性的认识。许多蛋白质被特异性地定位到紧密连接，包括细胞质肌动蛋白结合蛋白和黏附跨膜蛋白。后者包括紧密连接蛋白，它们是关键的屏障蛋白。目前的信息表明，细胞旁屏障最有用的模型是具有两个生理组成部分：一个半径为 4A 的电荷选择性小孔系统，和由屏障中较大不连续性形成的第二通道，该通道缺乏电荷或大小的区分。第一个途径受紧密连接蛋白表达模式的影响，第二个途径可能由不同的蛋白质和信号控制。最近关于紧密连接蛋白功能和致病突变的信息使我们对其在屏障形成中的作用有了更完整的认识，但由于缺乏高分辨率结构信息，进展受到阻碍。
