Figure 1.

A schematic diagram of the claudin (CLDN) protein structure. Claudin has four transmembrane structures, a highly conserved extracellular loop (ECL)-1 sequence, a monoclonal antibody binding site (claudin-18.2), and serine/threonine/tyrosine kinase binding sites on the C-terminal. Claudin tail is inserted into the cell membrane after palmitoylation.