Figure 1. Structure of tight junctions. The transmembrane proteins claudin and occludin, bind to intracellular zonula occludens (ZO) proteins. Junctional adhesion molecules (JAM)/coxsackievirus and adenovirus receptor (CAR), as transmembrane glycoproteins, bind to cingulin and/or multi-PDZ domain protein 1 (MUPP1). CAR is also attached to ZO-1. ZO proteins and cingulin link the tight junction structure to the actin filament.