Junctional adhesion molecules (JAMs) comprise a small subfamily of the immunoglobulin superfamily of adhesion receptors with a multitude of physiological functions in vertebrate development and homeostasis. Several members of the JAM family localize at tight junctions of epithelial and endothelial cells where they interact with PDZ domain-containing scaffolding proteins. For some JAM family members, molecular mechanisms have been elaborated through which they regulate cell-cell contact maturation and tight junction formation. For other members of this family our knowledge on their role in barrier-forming epithelia is still fragmentary. Here, we review our current understanding of the contribution of JAM family proteins to the barrier function of epithelial and endothelial cells with a major focus on epithelial tight junctions.

结粘附分子（JAM）包含粘附受体免疫球蛋白超家族的一小亚类，在脊椎动物的发育和体内平衡中具有多种生理功能。JAM家族的几个成员位于上皮细胞和内皮细胞的紧密连接处，在那里它们与包含PDZ域的支架蛋白相互作用。对于某些JAM家族成员，已经阐明了分子机制，通过它们调控细胞间接触成熟和紧密连接的形成。对于这个家庭的其他成员，我们对其在屏障形成上皮细胞中的作用的了解仍然是零碎的。在这里，我们回顾我们目前对JAM家族蛋白对上皮和内皮细胞的屏障功能的贡献的理解，主要侧重于上皮紧密连接。