An interaction between the extracellular C‐terminus of hCD98 and the PDZ class II domain of hCASK modulates intestinal barrier function

Cell junctions and adhesion molecules are present on the basolateral surfaces of intestinal epithelia. Here, we report that the hCD98 glycoprotein is heavily expressed on the basolateral membranes of intestinal epithelial cells, with the C‐terminus of itsextracellular domain protruding into the basolateral extracellularspace. The C‐terminus contains a PDZ class II‐binding domain (GLLLRFPYAA; amino acids 520–529), which was found to interact with the PDZ class II domain of the basolateral membrane‐associated guanylate kinase, hCASK. Furthermore, this extracellular PDZ‐dependent hCD98‐hCASK interaction was capable of modulating the barrier function of the intestinal epithelium.